diff --git a/src/Mutator/Arithmetic/Assignment.php b/src/Mutator/Arithmetic/Assignment.php
index bb86ea29b..e27c79891 100644
--- a/src/Mutator/Arithmetic/Assignment.php
+++ b/src/Mutator/Arithmetic/Assignment.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\Assign($node->var, $node->expr, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\AssignOp;
     }
diff --git a/src/Mutator/Arithmetic/AssignmentEqual.php b/src/Mutator/Arithmetic/AssignmentEqual.php
index 6faefff10..5d45828d3 100644
--- a/src/Mutator/Arithmetic/AssignmentEqual.php
+++ b/src/Mutator/Arithmetic/AssignmentEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\Assign($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Equal && $node->left instanceof Node\Expr\Variable;
     }
diff --git a/src/Mutator/Arithmetic/BitwiseAnd.php b/src/Mutator/Arithmetic/BitwiseAnd.php
index 6f479714b..41e85ec19 100644
--- a/src/Mutator/Arithmetic/BitwiseAnd.php
+++ b/src/Mutator/Arithmetic/BitwiseAnd.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\BitwiseOr($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\BitwiseAnd;
     }
diff --git a/src/Mutator/Arithmetic/BitwiseNot.php b/src/Mutator/Arithmetic/BitwiseNot.php
index 886bbfe87..13e3d0900 100644
--- a/src/Mutator/Arithmetic/BitwiseNot.php
+++ b/src/Mutator/Arithmetic/BitwiseNot.php
@@ -51,7 +51,7 @@ public function mutate(Node $node)
         return $node->expr;
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BitwiseNot;
     }
diff --git a/src/Mutator/Arithmetic/BitwiseOr.php b/src/Mutator/Arithmetic/BitwiseOr.php
index 21e2ce310..b2432761d 100644
--- a/src/Mutator/Arithmetic/BitwiseOr.php
+++ b/src/Mutator/Arithmetic/BitwiseOr.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\BitwiseAnd($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\BitwiseOr;
     }
diff --git a/src/Mutator/Arithmetic/BitwiseXor.php b/src/Mutator/Arithmetic/BitwiseXor.php
index 4008c6971..88bfc3291 100644
--- a/src/Mutator/Arithmetic/BitwiseXor.php
+++ b/src/Mutator/Arithmetic/BitwiseXor.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\BitwiseAnd($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\BitwiseXor;
     }
diff --git a/src/Mutator/Arithmetic/Decrement.php b/src/Mutator/Arithmetic/Decrement.php
index f5cb7bca3..88bc60b73 100644
--- a/src/Mutator/Arithmetic/Decrement.php
+++ b/src/Mutator/Arithmetic/Decrement.php
@@ -64,7 +64,7 @@ public function mutate(Node $node)
         }
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof PreDec || $node instanceof PostDec;
     }
diff --git a/src/Mutator/Arithmetic/DivEqual.php b/src/Mutator/Arithmetic/DivEqual.php
index b655044de..37f947b8e 100644
--- a/src/Mutator/Arithmetic/DivEqual.php
+++ b/src/Mutator/Arithmetic/DivEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\AssignOp\Mul($node->var, $node->expr, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\AssignOp\Div;
     }
diff --git a/src/Mutator/Arithmetic/Division.php b/src/Mutator/Arithmetic/Division.php
index cf909de20..fe77a923a 100644
--- a/src/Mutator/Arithmetic/Division.php
+++ b/src/Mutator/Arithmetic/Division.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Mul($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Div;
     }
diff --git a/src/Mutator/Arithmetic/Exponentiation.php b/src/Mutator/Arithmetic/Exponentiation.php
index 9c2751c65..27f7b78cd 100644
--- a/src/Mutator/Arithmetic/Exponentiation.php
+++ b/src/Mutator/Arithmetic/Exponentiation.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Div($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Pow;
     }
diff --git a/src/Mutator/Arithmetic/Increment.php b/src/Mutator/Arithmetic/Increment.php
index fa346bbd9..83902e057 100644
--- a/src/Mutator/Arithmetic/Increment.php
+++ b/src/Mutator/Arithmetic/Increment.php
@@ -64,7 +64,7 @@ public function mutate(Node $node)
         }
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof PreInc || $node instanceof PostInc;
     }
diff --git a/src/Mutator/Arithmetic/Minus.php b/src/Mutator/Arithmetic/Minus.php
index db6369d2b..4941b791c 100644
--- a/src/Mutator/Arithmetic/Minus.php
+++ b/src/Mutator/Arithmetic/Minus.php
@@ -53,7 +53,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Plus($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Minus;
     }
diff --git a/src/Mutator/Arithmetic/MinusEqual.php b/src/Mutator/Arithmetic/MinusEqual.php
index d5cde0a22..625d1a808 100644
--- a/src/Mutator/Arithmetic/MinusEqual.php
+++ b/src/Mutator/Arithmetic/MinusEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\AssignOp\Plus($node->var, $node->expr, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\AssignOp\Minus;
     }
diff --git a/src/Mutator/Arithmetic/ModEqual.php b/src/Mutator/Arithmetic/ModEqual.php
index 45be104e1..76f33438f 100644
--- a/src/Mutator/Arithmetic/ModEqual.php
+++ b/src/Mutator/Arithmetic/ModEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\AssignOp\Mul($node->var, $node->expr, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\AssignOp\Mod;
     }
diff --git a/src/Mutator/Arithmetic/Modulus.php b/src/Mutator/Arithmetic/Modulus.php
index 4a2550185..ab607e398 100644
--- a/src/Mutator/Arithmetic/Modulus.php
+++ b/src/Mutator/Arithmetic/Modulus.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Mul($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Mod;
     }
diff --git a/src/Mutator/Arithmetic/MulEqual.php b/src/Mutator/Arithmetic/MulEqual.php
index 33e8479e6..9d28c68a5 100644
--- a/src/Mutator/Arithmetic/MulEqual.php
+++ b/src/Mutator/Arithmetic/MulEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\AssignOp\Div($node->var, $node->expr, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\AssignOp\Mul;
     }
diff --git a/src/Mutator/Arithmetic/Multiplication.php b/src/Mutator/Arithmetic/Multiplication.php
index e918cb997..4557041fe 100644
--- a/src/Mutator/Arithmetic/Multiplication.php
+++ b/src/Mutator/Arithmetic/Multiplication.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Div($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Mul;
     }
diff --git a/src/Mutator/Arithmetic/Plus.php b/src/Mutator/Arithmetic/Plus.php
index 15ce112e3..ba24ae559 100644
--- a/src/Mutator/Arithmetic/Plus.php
+++ b/src/Mutator/Arithmetic/Plus.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Minus($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!($node instanceof Node\Expr\BinaryOp\Plus)) {
             return false;
diff --git a/src/Mutator/Arithmetic/PlusEqual.php b/src/Mutator/Arithmetic/PlusEqual.php
index 415896177..ede092f13 100644
--- a/src/Mutator/Arithmetic/PlusEqual.php
+++ b/src/Mutator/Arithmetic/PlusEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\AssignOp\Minus($node->var, $node->expr, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\AssignOp\Plus;
     }
diff --git a/src/Mutator/Arithmetic/PowEqual.php b/src/Mutator/Arithmetic/PowEqual.php
index 929772640..929c1148d 100644
--- a/src/Mutator/Arithmetic/PowEqual.php
+++ b/src/Mutator/Arithmetic/PowEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\AssignOp\Div($node->var, $node->expr, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\AssignOp\Pow;
     }
diff --git a/src/Mutator/Arithmetic/RoundingFamily.php b/src/Mutator/Arithmetic/RoundingFamily.php
index 7e067ba1a..d9ed2647e 100644
--- a/src/Mutator/Arithmetic/RoundingFamily.php
+++ b/src/Mutator/Arithmetic/RoundingFamily.php
@@ -74,7 +74,7 @@ public function mutate(Node $node)
         }
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Expr\FuncCall) {
             return false;
diff --git a/src/Mutator/Arithmetic/ShiftLeft.php b/src/Mutator/Arithmetic/ShiftLeft.php
index cdcb5f109..4510e9ac9 100644
--- a/src/Mutator/Arithmetic/ShiftLeft.php
+++ b/src/Mutator/Arithmetic/ShiftLeft.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\ShiftRight($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\ShiftLeft;
     }
diff --git a/src/Mutator/Arithmetic/ShiftRight.php b/src/Mutator/Arithmetic/ShiftRight.php
index cdfabd5ef..bd67d9e30 100644
--- a/src/Mutator/Arithmetic/ShiftRight.php
+++ b/src/Mutator/Arithmetic/ShiftRight.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\ShiftLeft($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\ShiftRight;
     }
diff --git a/src/Mutator/Boolean/ArrayItem.php b/src/Mutator/Boolean/ArrayItem.php
index 7991b0bdb..8ef967824 100644
--- a/src/Mutator/Boolean/ArrayItem.php
+++ b/src/Mutator/Boolean/ArrayItem.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Greater($node->key, $node->value, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\ArrayItem && $node->key && ($this->isNodeWithSideEffects($node->value) || $this->isNodeWithSideEffects($node->key));
     }
diff --git a/src/Mutator/Boolean/EqualIdentical.php b/src/Mutator/Boolean/EqualIdentical.php
index b8ad4ba4d..162ddfab5 100644
--- a/src/Mutator/Boolean/EqualIdentical.php
+++ b/src/Mutator/Boolean/EqualIdentical.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Identical($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Equal;
     }
diff --git a/src/Mutator/Boolean/FalseValue.php b/src/Mutator/Boolean/FalseValue.php
index a3b48172c..1be894982 100644
--- a/src/Mutator/Boolean/FalseValue.php
+++ b/src/Mutator/Boolean/FalseValue.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\ConstFetch(new Node\Name('true'));
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!($node instanceof Node\Expr\ConstFetch)) {
             return false;
diff --git a/src/Mutator/Boolean/IdenticalEqual.php b/src/Mutator/Boolean/IdenticalEqual.php
index 324a4d354..635b9c2f1 100644
--- a/src/Mutator/Boolean/IdenticalEqual.php
+++ b/src/Mutator/Boolean/IdenticalEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Equal($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Identical;
     }
diff --git a/src/Mutator/Boolean/LogicalAnd.php b/src/Mutator/Boolean/LogicalAnd.php
index 9357168f9..c90e2c897 100644
--- a/src/Mutator/Boolean/LogicalAnd.php
+++ b/src/Mutator/Boolean/LogicalAnd.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\BooleanOr($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\BooleanAnd;
     }
diff --git a/src/Mutator/Boolean/LogicalLowerAnd.php b/src/Mutator/Boolean/LogicalLowerAnd.php
index bf53268a5..88e679b0b 100644
--- a/src/Mutator/Boolean/LogicalLowerAnd.php
+++ b/src/Mutator/Boolean/LogicalLowerAnd.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\LogicalOr($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\LogicalAnd;
     }
diff --git a/src/Mutator/Boolean/LogicalLowerOr.php b/src/Mutator/Boolean/LogicalLowerOr.php
index 623cdb8fe..f4f23f1e4 100644
--- a/src/Mutator/Boolean/LogicalLowerOr.php
+++ b/src/Mutator/Boolean/LogicalLowerOr.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\LogicalAnd($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\LogicalOr;
     }
diff --git a/src/Mutator/Boolean/LogicalNot.php b/src/Mutator/Boolean/LogicalNot.php
index 4bbaaa805..57fb7bb5a 100644
--- a/src/Mutator/Boolean/LogicalNot.php
+++ b/src/Mutator/Boolean/LogicalNot.php
@@ -51,7 +51,7 @@ public function mutate(Node $node)
         return $node->expr;
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!($node instanceof Node\Expr\BooleanNot)) {
             return false;
diff --git a/src/Mutator/Boolean/LogicalOr.php b/src/Mutator/Boolean/LogicalOr.php
index bd4ff9909..eb61a921e 100644
--- a/src/Mutator/Boolean/LogicalOr.php
+++ b/src/Mutator/Boolean/LogicalOr.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\BooleanAnd($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\BooleanOr;
     }
diff --git a/src/Mutator/Boolean/NotEqualNotIdentical.php b/src/Mutator/Boolean/NotEqualNotIdentical.php
index ce1cbd476..911cbbb01 100644
--- a/src/Mutator/Boolean/NotEqualNotIdentical.php
+++ b/src/Mutator/Boolean/NotEqualNotIdentical.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\NotIdentical($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\NotEqual;
     }
diff --git a/src/Mutator/Boolean/NotIdenticalNotEqual.php b/src/Mutator/Boolean/NotIdenticalNotEqual.php
index 97bc0cd63..5c211c148 100644
--- a/src/Mutator/Boolean/NotIdenticalNotEqual.php
+++ b/src/Mutator/Boolean/NotIdenticalNotEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\NotEqual($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\NotIdentical;
     }
diff --git a/src/Mutator/Boolean/TrueValue.php b/src/Mutator/Boolean/TrueValue.php
index fc28b0b27..c4f312774 100644
--- a/src/Mutator/Boolean/TrueValue.php
+++ b/src/Mutator/Boolean/TrueValue.php
@@ -45,8 +45,8 @@
 final class TrueValue extends Mutator
 {
     private const DEFAULT_SETTINGS = [
-        'in_array' => false,
         'array_search' => false,
+        'in_array' => false,
     ];
 
     /**
@@ -60,7 +60,7 @@ public function mutate(Node $node)
         return new Node\Expr\ConstFetch(new Node\Name('false'));
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!($node instanceof Node\Expr\ConstFetch)) {
             return false;
@@ -73,16 +73,14 @@ protected function mutatesNode(Node $node, array $mutatorSettings): bool
         $parentNode = $node->getAttribute(ParentConnectorVisitor::PARENT_KEY);
         $grandParentNode = $parentNode !== null ? $parentNode->getAttribute(ParentConnectorVisitor::PARENT_KEY) : null;
 
-        if ($grandParentNode instanceof Node\Expr\FuncCall) {
-            $resultSettings = array_merge(self::DEFAULT_SETTINGS, $mutatorSettings);
+        if (!$grandParentNode instanceof Node\Expr\FuncCall || !$grandParentNode->name instanceof Node\Name) {
+            return true;
+        }
 
-            $functionName = $grandParentNode->name->toLowerString();
+        $resultSettings = array_merge(self::DEFAULT_SETTINGS, $this->config->getMutatorSettings());
 
-            if (array_key_exists($functionName, $resultSettings) && $resultSettings[$functionName] === false) {
-                return false;
-            }
-        }
+        $functionName = $grandParentNode->name->toLowerString();
 
-        return true;
+        return array_key_exists($functionName, $resultSettings) && $resultSettings[$functionName] !== false;
     }
 }
diff --git a/src/Mutator/Boolean/Yield_.php b/src/Mutator/Boolean/Yield_.php
index a6fc5b7d3..9897bdf01 100644
--- a/src/Mutator/Boolean/Yield_.php
+++ b/src/Mutator/Boolean/Yield_.php
@@ -57,7 +57,7 @@ public function mutate(Node $node)
         return $node;
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\Yield_ && $node->key;
     }
diff --git a/src/Mutator/Cast/CastArray.php b/src/Mutator/Cast/CastArray.php
index 23947079d..10bbe11cf 100644
--- a/src/Mutator/Cast/CastArray.php
+++ b/src/Mutator/Cast/CastArray.php
@@ -42,7 +42,7 @@
  */
 final class CastArray extends AbstractCastMutator
 {
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\Cast\Array_;
     }
diff --git a/src/Mutator/Cast/CastBool.php b/src/Mutator/Cast/CastBool.php
index dd3b872c8..9ad3fd062 100644
--- a/src/Mutator/Cast/CastBool.php
+++ b/src/Mutator/Cast/CastBool.php
@@ -42,7 +42,7 @@
  */
 final class CastBool extends AbstractCastMutator
 {
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\Cast\Bool_;
     }
diff --git a/src/Mutator/Cast/CastFloat.php b/src/Mutator/Cast/CastFloat.php
index 5fa887674..a03056e68 100644
--- a/src/Mutator/Cast/CastFloat.php
+++ b/src/Mutator/Cast/CastFloat.php
@@ -42,7 +42,7 @@
  */
 final class CastFloat extends AbstractCastMutator
 {
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\Cast\Double;
     }
diff --git a/src/Mutator/Cast/CastInt.php b/src/Mutator/Cast/CastInt.php
index 944f02077..567a9c685 100644
--- a/src/Mutator/Cast/CastInt.php
+++ b/src/Mutator/Cast/CastInt.php
@@ -42,7 +42,7 @@
  */
 final class CastInt extends AbstractCastMutator
 {
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\Cast\Int_;
     }
diff --git a/src/Mutator/Cast/CastObject.php b/src/Mutator/Cast/CastObject.php
index dba1dc162..49287945f 100644
--- a/src/Mutator/Cast/CastObject.php
+++ b/src/Mutator/Cast/CastObject.php
@@ -42,7 +42,7 @@
  */
 final class CastObject extends AbstractCastMutator
 {
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\Cast\Object_;
     }
diff --git a/src/Mutator/Cast/CastString.php b/src/Mutator/Cast/CastString.php
index fc8d5ec38..50e31b0db 100644
--- a/src/Mutator/Cast/CastString.php
+++ b/src/Mutator/Cast/CastString.php
@@ -42,7 +42,7 @@
  */
 final class CastString extends AbstractCastMutator
 {
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\Cast\String_;
     }
diff --git a/src/Mutator/ConditionalBoundary/GreaterThan.php b/src/Mutator/ConditionalBoundary/GreaterThan.php
index 9a874190d..4dfeaff83 100644
--- a/src/Mutator/ConditionalBoundary/GreaterThan.php
+++ b/src/Mutator/ConditionalBoundary/GreaterThan.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\GreaterOrEqual($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Greater;
     }
diff --git a/src/Mutator/ConditionalBoundary/GreaterThanOrEqualTo.php b/src/Mutator/ConditionalBoundary/GreaterThanOrEqualTo.php
index 660c51eb4..b34762405 100644
--- a/src/Mutator/ConditionalBoundary/GreaterThanOrEqualTo.php
+++ b/src/Mutator/ConditionalBoundary/GreaterThanOrEqualTo.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Greater($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\GreaterOrEqual;
     }
diff --git a/src/Mutator/ConditionalBoundary/LessThan.php b/src/Mutator/ConditionalBoundary/LessThan.php
index 486a722d2..d1f865028 100644
--- a/src/Mutator/ConditionalBoundary/LessThan.php
+++ b/src/Mutator/ConditionalBoundary/LessThan.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\SmallerOrEqual($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Smaller;
     }
diff --git a/src/Mutator/ConditionalBoundary/LessThanOrEqualTo.php b/src/Mutator/ConditionalBoundary/LessThanOrEqualTo.php
index 7cd0e2d87..e561aa8d8 100644
--- a/src/Mutator/ConditionalBoundary/LessThanOrEqualTo.php
+++ b/src/Mutator/ConditionalBoundary/LessThanOrEqualTo.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Smaller($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\SmallerOrEqual;
     }
diff --git a/src/Mutator/ConditionalNegotiation/Equal.php b/src/Mutator/ConditionalNegotiation/Equal.php
index e9b1eddac..32691bbdf 100644
--- a/src/Mutator/ConditionalNegotiation/Equal.php
+++ b/src/Mutator/ConditionalNegotiation/Equal.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\NotEqual($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Equal;
     }
diff --git a/src/Mutator/ConditionalNegotiation/GreaterThanNegotiation.php b/src/Mutator/ConditionalNegotiation/GreaterThanNegotiation.php
index d64519a8b..7cfec98a5 100644
--- a/src/Mutator/ConditionalNegotiation/GreaterThanNegotiation.php
+++ b/src/Mutator/ConditionalNegotiation/GreaterThanNegotiation.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\SmallerOrEqual($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Greater;
     }
diff --git a/src/Mutator/ConditionalNegotiation/GreaterThanOrEqualToNegotiation.php b/src/Mutator/ConditionalNegotiation/GreaterThanOrEqualToNegotiation.php
index bb7646ea1..f86a65068 100644
--- a/src/Mutator/ConditionalNegotiation/GreaterThanOrEqualToNegotiation.php
+++ b/src/Mutator/ConditionalNegotiation/GreaterThanOrEqualToNegotiation.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Smaller($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\GreaterOrEqual;
     }
diff --git a/src/Mutator/ConditionalNegotiation/Identical.php b/src/Mutator/ConditionalNegotiation/Identical.php
index f838b4240..df3d23473 100644
--- a/src/Mutator/ConditionalNegotiation/Identical.php
+++ b/src/Mutator/ConditionalNegotiation/Identical.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\NotIdentical($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Identical;
     }
diff --git a/src/Mutator/ConditionalNegotiation/LessThanNegotiation.php b/src/Mutator/ConditionalNegotiation/LessThanNegotiation.php
index c1911b7b4..cfb87af96 100644
--- a/src/Mutator/ConditionalNegotiation/LessThanNegotiation.php
+++ b/src/Mutator/ConditionalNegotiation/LessThanNegotiation.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\GreaterOrEqual($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Smaller;
     }
diff --git a/src/Mutator/ConditionalNegotiation/LessThanOrEqualToNegotiation.php b/src/Mutator/ConditionalNegotiation/LessThanOrEqualToNegotiation.php
index ff0fe2b0d..45dfbc066 100644
--- a/src/Mutator/ConditionalNegotiation/LessThanOrEqualToNegotiation.php
+++ b/src/Mutator/ConditionalNegotiation/LessThanOrEqualToNegotiation.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Greater($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\SmallerOrEqual;
     }
diff --git a/src/Mutator/ConditionalNegotiation/NotEqual.php b/src/Mutator/ConditionalNegotiation/NotEqual.php
index 0d42e5857..4bf747d43 100644
--- a/src/Mutator/ConditionalNegotiation/NotEqual.php
+++ b/src/Mutator/ConditionalNegotiation/NotEqual.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Equal($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\NotEqual;
     }
diff --git a/src/Mutator/ConditionalNegotiation/NotIdentical.php b/src/Mutator/ConditionalNegotiation/NotIdentical.php
index a588fac2a..f744c08b2 100644
--- a/src/Mutator/ConditionalNegotiation/NotIdentical.php
+++ b/src/Mutator/ConditionalNegotiation/NotIdentical.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Identical($node->left, $node->right, $node->getAttributes());
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\NotIdentical;
     }
diff --git a/src/Mutator/FunctionSignature/ProtectedVisibility.php b/src/Mutator/FunctionSignature/ProtectedVisibility.php
index e84503949..5c55917f7 100644
--- a/src/Mutator/FunctionSignature/ProtectedVisibility.php
+++ b/src/Mutator/FunctionSignature/ProtectedVisibility.php
@@ -68,7 +68,7 @@ public function mutate(Node $node)
         );
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof ClassMethod) {
             return false;
diff --git a/src/Mutator/FunctionSignature/PublicVisibility.php b/src/Mutator/FunctionSignature/PublicVisibility.php
index b62741c29..82782ce73 100644
--- a/src/Mutator/FunctionSignature/PublicVisibility.php
+++ b/src/Mutator/FunctionSignature/PublicVisibility.php
@@ -71,7 +71,7 @@ public function mutate(Node $node)
         );
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof ClassMethod) {
             return false;
diff --git a/src/Mutator/Number/DecrementInteger.php b/src/Mutator/Number/DecrementInteger.php
index a6abf8173..8a617bafa 100644
--- a/src/Mutator/Number/DecrementInteger.php
+++ b/src/Mutator/Number/DecrementInteger.php
@@ -57,7 +57,7 @@ public function mutate(Node $node)
         return new Node\Scalar\LNumber($node->value - 1);
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Scalar\LNumber || $node->value === 1) {
             return false;
diff --git a/src/Mutator/Number/IncrementInteger.php b/src/Mutator/Number/IncrementInteger.php
index 7479cd770..33474da85 100644
--- a/src/Mutator/Number/IncrementInteger.php
+++ b/src/Mutator/Number/IncrementInteger.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Scalar\LNumber($node->value + 1);
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Scalar\LNumber && $node->value !== 0;
     }
diff --git a/src/Mutator/Number/OneZeroFloat.php b/src/Mutator/Number/OneZeroFloat.php
index 1e028cf9b..f5af2b2bc 100644
--- a/src/Mutator/Number/OneZeroFloat.php
+++ b/src/Mutator/Number/OneZeroFloat.php
@@ -58,7 +58,7 @@ public function mutate(Node $node)
         return new Node\Scalar\DNumber(0.0);
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Scalar\DNumber && ($node->value === 0.0 || $node->value === 1.0);
     }
diff --git a/src/Mutator/Number/OneZeroInteger.php b/src/Mutator/Number/OneZeroInteger.php
index f716254e1..27d2fe71d 100644
--- a/src/Mutator/Number/OneZeroInteger.php
+++ b/src/Mutator/Number/OneZeroInteger.php
@@ -58,7 +58,7 @@ public function mutate(Node $node)
         return new Node\Scalar\LNumber(0);
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Scalar\LNumber && ($node->value === 0 || $node->value === 1);
     }
diff --git a/src/Mutator/Operator/Break_.php b/src/Mutator/Operator/Break_.php
index f27d6e3f0..325febe00 100644
--- a/src/Mutator/Operator/Break_.php
+++ b/src/Mutator/Operator/Break_.php
@@ -55,7 +55,7 @@ public function mutate(Node $node)
         return new Node\Stmt\Continue_();
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Break_) {
             return false;
diff --git a/src/Mutator/Operator/Coalesce.php b/src/Mutator/Operator/Coalesce.php
index 077f29ccd..a6ce7f458 100644
--- a/src/Mutator/Operator/Coalesce.php
+++ b/src/Mutator/Operator/Coalesce.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return $node->right;
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Coalesce;
     }
diff --git a/src/Mutator/Operator/Continue_.php b/src/Mutator/Operator/Continue_.php
index 0f3eb11e0..01732836a 100644
--- a/src/Mutator/Operator/Continue_.php
+++ b/src/Mutator/Operator/Continue_.php
@@ -55,7 +55,7 @@ public function mutate(Node $node)
         return new Node\Stmt\Break_();
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Continue_) {
             return false;
diff --git a/src/Mutator/Operator/Finally_.php b/src/Mutator/Operator/Finally_.php
index 0e139117f..4d45b17d3 100644
--- a/src/Mutator/Operator/Finally_.php
+++ b/src/Mutator/Operator/Finally_.php
@@ -55,7 +55,7 @@ public function mutate(Node $node)
         return new Node\Stmt\Nop();
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Finally_) {
             return false;
diff --git a/src/Mutator/Operator/Throw_.php b/src/Mutator/Operator/Throw_.php
index 73b1007b8..e3574910e 100644
--- a/src/Mutator/Operator/Throw_.php
+++ b/src/Mutator/Operator/Throw_.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Stmt\Expression($node->expr);
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Stmt\Throw_;
     }
diff --git a/src/Mutator/Regex/PregMatchMatches.php b/src/Mutator/Regex/PregMatchMatches.php
index 3c2536477..f13d8db87 100644
--- a/src/Mutator/Regex/PregMatchMatches.php
+++ b/src/Mutator/Regex/PregMatchMatches.php
@@ -55,7 +55,7 @@ public function mutate(Node $node)
         return new Node\Expr\Cast\Int_(new Node\Expr\Assign($node->args[2]->value, new Node\Expr\Array_()));
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Expr\FuncCall) {
             return false;
diff --git a/src/Mutator/Regex/PregQuote.php b/src/Mutator/Regex/PregQuote.php
index ae102739c..561d9af80 100644
--- a/src/Mutator/Regex/PregQuote.php
+++ b/src/Mutator/Regex/PregQuote.php
@@ -51,7 +51,7 @@ public function mutate(Node $node)
         return $node->args[0];
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\FuncCall &&
             $node->name instanceof Node\Name &&
diff --git a/src/Mutator/Removal/FunctionCallRemoval.php b/src/Mutator/Removal/FunctionCallRemoval.php
index bf67ab352..5918551ff 100644
--- a/src/Mutator/Removal/FunctionCallRemoval.php
+++ b/src/Mutator/Removal/FunctionCallRemoval.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Stmt\Nop();
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Expression) {
             return false;
diff --git a/src/Mutator/Removal/MethodCallRemoval.php b/src/Mutator/Removal/MethodCallRemoval.php
index bdd747e43..2a0e23edb 100644
--- a/src/Mutator/Removal/MethodCallRemoval.php
+++ b/src/Mutator/Removal/MethodCallRemoval.php
@@ -54,7 +54,7 @@ public function mutate(Node $node)
         return new Node\Stmt\Nop();
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Expression) {
             return false;
diff --git a/src/Mutator/ReturnValue/FloatNegation.php b/src/Mutator/ReturnValue/FloatNegation.php
index bd1bd36c4..183ee93bd 100644
--- a/src/Mutator/ReturnValue/FloatNegation.php
+++ b/src/Mutator/ReturnValue/FloatNegation.php
@@ -61,7 +61,7 @@ public function mutate(Node $node)
         );
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Return_) {
             return false;
diff --git a/src/Mutator/ReturnValue/FunctionCall.php b/src/Mutator/ReturnValue/FunctionCall.php
index aeeda5dec..9c5d37101 100644
--- a/src/Mutator/ReturnValue/FunctionCall.php
+++ b/src/Mutator/ReturnValue/FunctionCall.php
@@ -59,7 +59,7 @@ public function mutate(Node $node)
         ];
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Return_) {
             return false;
diff --git a/src/Mutator/ReturnValue/IntegerNegation.php b/src/Mutator/ReturnValue/IntegerNegation.php
index 27ea49184..9383f5cc0 100644
--- a/src/Mutator/ReturnValue/IntegerNegation.php
+++ b/src/Mutator/ReturnValue/IntegerNegation.php
@@ -61,7 +61,7 @@ public function mutate(Node $node)
         );
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Return_) {
             return false;
diff --git a/src/Mutator/ReturnValue/NewObject.php b/src/Mutator/ReturnValue/NewObject.php
index d1309ef90..bd9e9258b 100644
--- a/src/Mutator/ReturnValue/NewObject.php
+++ b/src/Mutator/ReturnValue/NewObject.php
@@ -59,7 +59,7 @@ public function mutate(Node $node)
         ];
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Stmt\Return_) {
             return false;
diff --git a/src/Mutator/ReturnValue/This.php b/src/Mutator/ReturnValue/This.php
index 1b91ce1ed..78274771e 100644
--- a/src/Mutator/ReturnValue/This.php
+++ b/src/Mutator/ReturnValue/This.php
@@ -56,7 +56,7 @@ public function mutate(Node $node)
         );
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Stmt\Return_ &&
             $node->expr instanceof Node\Expr\Variable &&
diff --git a/src/Mutator/Sort/Spaceship.php b/src/Mutator/Sort/Spaceship.php
index 81e84278d..c8e6986f2 100644
--- a/src/Mutator/Sort/Spaceship.php
+++ b/src/Mutator/Sort/Spaceship.php
@@ -55,7 +55,7 @@ public function mutate(Node $node)
         return new Node\Expr\BinaryOp\Spaceship($node->right, $node->left);
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Expr\BinaryOp\Spaceship;
     }
diff --git a/src/Mutator/Unwrap/AbstractUnwrapMutator.php b/src/Mutator/Unwrap/AbstractUnwrapMutator.php
index a9676ac7f..086590941 100644
--- a/src/Mutator/Unwrap/AbstractUnwrapMutator.php
+++ b/src/Mutator/Unwrap/AbstractUnwrapMutator.php
@@ -59,7 +59,7 @@ abstract protected function getFunctionName(): string;
 
     abstract protected function getParameterIndexes(Node $node): \Generator;
 
-    final protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    final protected function mutatesNode(Node $node): bool
     {
         if (!$node instanceof Node\Expr\FuncCall || !$node->name instanceof Node\Name) {
             return false;
diff --git a/src/Mutator/Util/Mutator.php b/src/Mutator/Util/Mutator.php
index 5d0e80f56..d22f62071 100644
--- a/src/Mutator/Util/Mutator.php
+++ b/src/Mutator/Util/Mutator.php
@@ -43,7 +43,7 @@ abstract class Mutator
     /**
      * @var MutatorConfig
      */
-    private $config;
+    protected $config;
 
     public function __construct(MutatorConfig $config)
     {
@@ -57,7 +57,7 @@ abstract public function mutate(Node $node);
 
     final public function shouldMutate(Node $node): bool
     {
-        if (!$this->mutatesNode($node, $this->config->getMutatorSettings())) {
+        if (!$this->mutatesNode($node)) {
             return false;
         }
 
@@ -77,5 +77,5 @@ final public static function getName(): string
         return end($parts);
     }
 
-    abstract protected function mutatesNode(Node $node, array $mutatorSettings): bool;
+    abstract protected function mutatesNode(Node $node): bool;
 }
diff --git a/src/Mutator/ZeroIteration/For_.php b/src/Mutator/ZeroIteration/For_.php
index 5b87b4e47..418395f27 100644
--- a/src/Mutator/ZeroIteration/For_.php
+++ b/src/Mutator/ZeroIteration/For_.php
@@ -62,7 +62,7 @@ public function mutate(Node $node)
         );
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Stmt\For_;
     }
diff --git a/src/Mutator/ZeroIteration/Foreach_.php b/src/Mutator/ZeroIteration/Foreach_.php
index 966dc6e14..ab514e451 100644
--- a/src/Mutator/ZeroIteration/Foreach_.php
+++ b/src/Mutator/ZeroIteration/Foreach_.php
@@ -63,7 +63,7 @@ public function mutate(Node $node)
         );
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         return $node instanceof Node\Stmt\Foreach_;
     }
diff --git a/tests/Fixtures/Autoloaded/Mutator/ErrorMutator.php b/tests/Fixtures/Autoloaded/Mutator/ErrorMutator.php
index 987c647b1..60388f5c2 100644
--- a/tests/Fixtures/Autoloaded/Mutator/ErrorMutator.php
+++ b/tests/Fixtures/Autoloaded/Mutator/ErrorMutator.php
@@ -13,7 +13,7 @@ public function mutate(Node $node)
         return $node;
     }
 
-    protected function mutatesNode(Node $node, array $mutatorSettings): bool
+    protected function mutatesNode(Node $node): bool
     {
         //This is intended to cause an error.
         $name = (string) $node;
diff --git a/tests/Fixtures/StubMutator.php b/tests/Fixtures/StubMutator.php
index f38da9f5d..4c65486af 100644
--- a/tests/Fixtures/StubMutator.php
+++ b/tests/Fixtures/StubMutator.php
@@ -12,7 +12,7 @@ public function mutate(Node $node)
     {
     }
 
-    public function mutatesNode(Node $node, array $mutatorSettings): bool
+    public function mutatesNode(Node $node): bool
     {
         return false;
     }
diff --git a/tests/Json/JsonFileTest.php b/tests/Json/JsonFileTest.php
index b301cc775..6fdbb9b26 100644
--- a/tests/Json/JsonFileTest.php
+++ b/tests/Json/JsonFileTest.php
@@ -135,8 +135,8 @@ public function validTrueValueProvider(): \Generator
 {
     "timeout": 25,
     "source": {"directories": ["src"]},
-	"mutators": {
-      "TrueValue": true
+    "mutators": {
+        "TrueValue": true
     }
 }
 JSON
@@ -146,17 +146,19 @@ public function validTrueValueProvider(): \Generator
             <<<JSON
 {
     "timeout": 25,
-    "source": {"directories": ["src"]},
-	"mutators": {
-      "TrueValue": {
-        "ignore": [
-            "IgnoreClass"
-        ],
-      	"settings": {
-        	"in_array": false,
-            "array_search": true
+    "source": {
+        "directories": ["src"]
+    },
+    "mutators": {
+        "TrueValue": {
+            "ignore": [
+                "IgnoreClass"
+            ],
+            "settings": {
+                "in_array": false,
+                "array_search": true
+            }
         }
-      }
     }
 }
 JSON
@@ -185,17 +187,17 @@ public function invalidTrueValueProvider(): \Generator
 {
     "timeout": 25,
     "source": {"directories": ["src"]},
-	"mutators": {
-      "TrueValue": {
-        "EXTRA_KEY": true,
-        "ignore": [
-            "IgnoreClass"
-        ],
-      	"settings": {
-        	"in_array": false,
-            "array_search": true
+    "mutators": {
+        "TrueValue": {
+            "EXTRA_KEY": true,
+            "ignore": [
+                "IgnoreClass"
+            ],
+            "settings": {
+                "in_array": false,
+                "array_search": true
+            }
         }
-      }
     }
 }
 JSON
@@ -208,17 +210,17 @@ public function invalidTrueValueProvider(): \Generator
 {
     "timeout": 25,
     "source": {"directories": ["src"]},
-	"mutators": {
-      "TrueValue": {
-        "ignore": [
-            "IgnoreClass"
-        ],
-      	"settings": {
-      	    "EXTRA_KEY": true,
-        	"in_array": false,
-            "array_search": true
+    "mutators": {
+        "TrueValue": {
+            "ignore": [
+                "IgnoreClass"
+            ],
+            "settings": {
+                "EXTRA_KEY": true,
+                "in_array": false,
+                "array_search": true
+            }
         }
-      }
     }
 }
 JSON
@@ -231,16 +233,16 @@ public function invalidTrueValueProvider(): \Generator
 {
     "timeout": 25,
     "source": {"directories": ["src"]},
-	"mutators": {
-      "TrueValue": {
-        "ignore": [
-            "IgnoreClass"
-        ],
-      	"settings": {
-        	"in_array": 123,
-            "array_search": true
+    "mutators": {
+        "TrueValue": {
+            "ignore": [
+                "IgnoreClass"
+            ],
+            "settings": {
+                "in_array": 123,
+                "array_search": true
+            }
         }
-      }
     }
 }
 JSON
@@ -253,8 +255,8 @@ public function invalidTrueValueProvider(): \Generator
 {
     "timeout": 25,
     "source": {"directories": ["src"]},
-	"mutators": {
-      "TrueValue": 123
+    "mutators": {
+        "TrueValue": 123
     }
 }
 JSON
diff --git a/tests/Mutator/AbstractMutatorTestCase.php b/tests/Mutator/AbstractMutatorTestCase.php
index bdf782aa6..0510faf69 100644
--- a/tests/Mutator/AbstractMutatorTestCase.php
+++ b/tests/Mutator/AbstractMutatorTestCase.php
@@ -66,7 +66,7 @@ protected function setUp(): void
         $this->mutator = $this->getMutator();
     }
 
-    public function doTest(string $inputCode, $expectedCode = null, $settings = []): void
+    public function doTest(string $inputCode, $expectedCode = null, array $settings = []): void
     {
         $expectedCodeSamples = (array) $expectedCode;
 
diff --git a/tests/Mutator/Boolean/TrueValueTest.php b/tests/Mutator/Boolean/TrueValueTest.php
index 72e5ed3bc..232b60d5e 100644
--- a/tests/Mutator/Boolean/TrueValueTest.php
+++ b/tests/Mutator/Boolean/TrueValueTest.php
@@ -47,7 +47,7 @@ final class TrueValueTest extends AbstractMutatorTestCase
     /**
      * @dataProvider provideMutationCases
      */
-    public function test_mutator($input, $expected = null, $settings = []): void
+    public function test_mutator($input, $expected = null, array $settings = []): void
     {
         $this->doTest($input, $expected, $settings);
     }
@@ -65,6 +65,38 @@ public function provideMutationCases(): \Generator
 <?php
 
 return false;
+PHP
+                ,
+            ];
+
+        yield 'It mutates inside function call when function is a variable' => [
+                <<<'PHP'
+<?php
+
+$a = 'foo';
+$a(true);
+PHP
+                ,
+                <<<'PHP'
+<?php
+
+$a = 'foo';
+$a(false);
+PHP
+                ,
+            ];
+
+        yield 'It mutates inside function call when function is a string' => [
+                <<<'PHP'
+<?php
+
+('function_name')(true);
+PHP
+                ,
+                <<<'PHP'
+<?php
+
+('function_name')(false);
 PHP
                 ,
             ];
@@ -190,17 +222,17 @@ public function provideMutationCases(): \Generator
             ,
         ];
 
-        yield 'It mutates when used in "\array_search" function and explicitly enabled in settings' => [
+        yield 'It mutates when used in "array_search" function and explicitly enabled in settings' => [
             <<<'PHP'
 <?php
 
-\array_search($a, $b, true);
+array_search($a, $b, true);
 PHP
             ,
             <<<'PHP'
 <?php
 
-\array_search($a, $b, false);
+array_search($a, $b, false);
 PHP
             ,
             [
@@ -213,6 +245,19 @@ public function provideMutationCases(): \Generator
 <?php
 
 \array_search($a, $b, true);
+PHP
+            ,
+            [],
+            [
+                'settings' => ['array_search' => false],
+            ],
+        ];
+
+        yield 'It does not mutate when used in "\array_search" function and explicitly disabled and function is wrongly capitalized' => [
+            <<<'PHP'
+<?php
+
+\aRrAy_SeArCh($a, $b, true);
 PHP
             ,
             [],