diff --git a/src/Methods/BuilderHelper.php b/src/Methods/BuilderHelper.php
index b5ba994de..a9fbefd15 100644
--- a/src/Methods/BuilderHelper.php
+++ b/src/Methods/BuilderHelper.php
@@ -22,6 +22,7 @@
 use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeWithClassName;
 use PHPStan\Type\VerbosityLevel;
 
 class BuilderHelper
@@ -211,7 +212,7 @@ public function determineBuilderName(string $modelClassName): string
             return EloquentBuilder::class;
         }
 
-        if ($returnType instanceof ObjectType) {
+        if ($returnType instanceof TypeWithClassName) {
             return $returnType->getClassName();
         }
 
@@ -223,7 +224,7 @@ public function determineCollectionClassName(string $modelClassName): string
         try {
             $newCollectionMethod = $this->reflectionProvider->getClass($modelClassName)->getNativeMethod('newCollection');
             $returnType = ParametersAcceptorSelector::selectSingle($newCollectionMethod->getVariants())->getReturnType();
-            if ($returnType instanceof ObjectType) {
+            if ($returnType instanceof TypeWithClassName) {
                 return $returnType->getClassName();
             }
 
diff --git a/src/Methods/HigherOrderTapProxyExtension.php b/src/Methods/HigherOrderTapProxyExtension.php
index 8fcbbc0a5..4593585c4 100644
--- a/src/Methods/HigherOrderTapProxyExtension.php
+++ b/src/Methods/HigherOrderTapProxyExtension.php
@@ -10,6 +10,7 @@
 use PHPStan\Reflection\MethodReflection;
 use PHPStan\Reflection\MethodsClassReflectionExtension;
 use PHPStan\Type\ObjectType;
+use PHPStan\Type\TypeWithClassName;
 
 final class HigherOrderTapProxyExtension implements MethodsClassReflectionExtension
 {
@@ -23,7 +24,7 @@ public function hasMethod(ClassReflection $classReflection, string $methodName):
 
         $templateType = $templateTypeMap->getType('TClass');
 
-        if (! $templateType instanceof ObjectType) {
+        if (! $templateType instanceof TypeWithClassName) {
             return false;
         }
 
diff --git a/src/ReturnTypes/BuilderModelFindExtension.php b/src/ReturnTypes/BuilderModelFindExtension.php
index 23ff724b7..f1fa4d650 100644
--- a/src/ReturnTypes/BuilderModelFindExtension.php
+++ b/src/ReturnTypes/BuilderModelFindExtension.php
@@ -22,6 +22,7 @@
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\TypeWithClassName;
 
 /**
  * @internal
@@ -61,7 +62,7 @@ public function isMethodSupported(MethodReflection $methodReflection): bool
 
         $model = $methodReflection->getDeclaringClass()->getActiveTemplateTypeMap()->getType('TModelClass');
 
-        if (! $model instanceof ObjectType) {
+        if (! $model instanceof TypeWithClassName) {
             return false;
         }
 
diff --git a/src/ReturnTypes/CollectionGenericStaticMethodDynamicMethodReturnTypeExtension.php b/src/ReturnTypes/CollectionGenericStaticMethodDynamicMethodReturnTypeExtension.php
index 77be35a52..8c125e90a 100644
--- a/src/ReturnTypes/CollectionGenericStaticMethodDynamicMethodReturnTypeExtension.php
+++ b/src/ReturnTypes/CollectionGenericStaticMethodDynamicMethodReturnTypeExtension.php
@@ -17,6 +17,7 @@
 use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeTraverser;
+use PHPStan\Type\TypeWithClassName;
 use PHPStan\Type\UnionType;
 
 class CollectionGenericStaticMethodDynamicMethodReturnTypeExtension implements DynamicMethodReturnTypeExtension
@@ -62,7 +63,7 @@ public function getTypeFromMethodCall(
 
         $calledOnType = $scope->getType($methodCall->var);
 
-        if (! $calledOnType instanceof ObjectType) {
+        if (! $calledOnType instanceof TypeWithClassName) {
             return $returnType;
         }
 
diff --git a/src/ReturnTypes/EloquentBuilderExtension.php b/src/ReturnTypes/EloquentBuilderExtension.php
index 9a96206b7..4da89792d 100644
--- a/src/ReturnTypes/EloquentBuilderExtension.php
+++ b/src/ReturnTypes/EloquentBuilderExtension.php
@@ -19,6 +19,7 @@
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeWithClassName;
 
 final class EloquentBuilderExtension implements DynamicMethodReturnTypeExtension
 {
@@ -58,7 +59,7 @@ public function isMethodSupported(MethodReflection $methodReflection): bool
 
         $templateTypeMap = $methodReflection->getDeclaringClass()->getActiveTemplateTypeMap();
 
-        if (! $templateTypeMap->getType('TModelClass') instanceof ObjectType) {
+        if (! $templateTypeMap->getType('TModelClass') instanceof TypeWithClassName) {
             return false;
         }
 
diff --git a/src/ReturnTypes/HigherOrderTapProxyExtension.php b/src/ReturnTypes/HigherOrderTapProxyExtension.php
index f39e13f9b..31ff625bb 100644
--- a/src/ReturnTypes/HigherOrderTapProxyExtension.php
+++ b/src/ReturnTypes/HigherOrderTapProxyExtension.php
@@ -11,8 +11,8 @@
 use PHPStan\Type\DynamicMethodReturnTypeExtension;
 use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\MixedType;
-use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeWithClassName;
 
 /**
  * @internal
@@ -46,7 +46,7 @@ public function getTypeFromMethodCall(
         $type = $scope->getType($methodCall->var);
         if ($type instanceof GenericObjectType) {
             $types = $type->getTypes();
-            if (count($types) === 1 && $types[0] instanceof ObjectType) {
+            if (count($types) === 1 && $types[0] instanceof TypeWithClassName) {
                 return $types[0];
             }
         }
diff --git a/src/ReturnTypes/RelationCollectionExtension.php b/src/ReturnTypes/RelationCollectionExtension.php
index 7295a299c..6a05c8f16 100644
--- a/src/ReturnTypes/RelationCollectionExtension.php
+++ b/src/ReturnTypes/RelationCollectionExtension.php
@@ -17,6 +17,7 @@
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeWithClassName;
 
 /**
  * @internal
@@ -50,7 +51,7 @@ public function isMethodSupported(MethodReflection $methodReflection): bool
 
         $modelType = $methodReflection->getDeclaringClass()->getActiveTemplateTypeMap()->getType('TRelatedModel');
 
-        if (! $modelType instanceof ObjectType) {
+        if (! $modelType instanceof TypeWithClassName) {
             return false;
         }
 
diff --git a/src/ReturnTypes/RelationFindExtension.php b/src/ReturnTypes/RelationFindExtension.php
index 7bb1dd882..a62dc5897 100644
--- a/src/ReturnTypes/RelationFindExtension.php
+++ b/src/ReturnTypes/RelationFindExtension.php
@@ -22,6 +22,7 @@
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\TypeWithClassName;
 
 /**
  * @internal
@@ -59,7 +60,7 @@ public function isMethodSupported(MethodReflection $methodReflection): bool
 
         $modelType = $methodReflection->getDeclaringClass()->getActiveTemplateTypeMap()->getType('TRelatedModel');
 
-        if (! $modelType instanceof ObjectType) {
+        if (! $modelType instanceof TypeWithClassName) {
             return false;
         }
 
diff --git a/src/Rules/ModelProperties/ModelPropertiesRuleHelper.php b/src/Rules/ModelProperties/ModelPropertiesRuleHelper.php
index fecfe7c89..42e8fc1b7 100644
--- a/src/Rules/ModelProperties/ModelPropertiesRuleHelper.php
+++ b/src/Rules/ModelProperties/ModelPropertiesRuleHelper.php
@@ -14,8 +14,6 @@
 use PHPStan\Reflection\MethodReflection;
 use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\ShouldNotHappenException;
-use PHPStan\Type\ArrayType;
-use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
@@ -62,17 +60,21 @@ public function check(MethodReflection $methodReflection, Scope $scope, array $a
 
         $argType = $scope->getType($argValue);
 
-        if ($argType instanceof ConstantArrayType) {
+        if ($argType->isConstantArray()->yes()) {
             $errors = [];
 
-            $keyType = $argType->getKeyType()->generalize(GeneralizePrecision::lessSpecific());
+            $constantArrays = $argType->getConstantArrays();
 
-            if ($keyType->isInteger()->yes()) {
-                $valueTypes = $argType->getValuesArray()->getValueTypes();
-            } elseif ($keyType->isString()->yes()) {
-                $valueTypes = $argType->getKeysArray()->getValueTypes();
-            } else {
-                $valueTypes = [];
+            $valueTypes = [];
+
+            foreach ($constantArrays as $constantArray) {
+                $keyType = $constantArray->getKeyType()->generalize(GeneralizePrecision::lessSpecific());
+
+                if ($keyType->isInteger()->yes()) {
+                    $valueTypes = array_merge($valueTypes, $constantArray->getValuesArray()->getValueTypes());
+                } elseif ($keyType->isString()->yes()) {
+                    $valueTypes = array_merge($valueTypes, $constantArray->getKeysArray()->getValueTypes());
+                }
             }
 
             foreach ($valueTypes as $valueType) {
@@ -159,9 +161,9 @@ public function hasModelPropertyParameter(
                         return [$index, new ObjectType($modelReflection->getName())];
                     }
                 }
-            } elseif ($type instanceof ArrayType) {
-                $keyType = $type->getKeyType();
-                $itemType = $type->getItemType();
+            } elseif ($type->isArray()->yes()) {
+                $keyType = $type->getIterableKeyType();
+                $itemType = $type->getIterableValueType();
 
                 if ($keyType instanceof GenericModelPropertyType) {
                     return [$index, $keyType->getGenericType()];
diff --git a/src/Rules/ModelProperties/ModelPropertyStaticCallRule.php b/src/Rules/ModelProperties/ModelPropertyStaticCallRule.php
index e5ee18880..a8a738cb2 100644
--- a/src/Rules/ModelProperties/ModelPropertyStaticCallRule.php
+++ b/src/Rules/ModelProperties/ModelPropertyStaticCallRule.php
@@ -13,10 +13,10 @@
 use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleLevelHelper;
-use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\ErrorType;
-use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeUtils;
+use PHPStan\Type\TypeWithClassName;
 
 /**
  * @implements \PHPStan\Rules\Rule<\PhpParser\Node\Expr\StaticCall>
@@ -116,9 +116,11 @@ static function (Type $type) use ($methodName): bool {
                 return [];
             }
 
-            if ($classType instanceof ConstantStringType) {
-                $modelClassName = $classType->getValue();
-            } elseif ($classType instanceof ObjectType) {
+            $strings = TypeUtils::getConstantStrings($classType);
+
+            if (count($strings) === 1) {
+                $modelClassName = $strings[0]->getValue();
+            } elseif ($classType instanceof TypeWithClassName) {
                 $modelClassName = $classType->getClassName();
             } else {
                 return [];
diff --git a/src/Rules/ModelRuleHelper.php b/src/Rules/ModelRuleHelper.php
index 10d12f38c..19e2384c4 100644
--- a/src/Rules/ModelRuleHelper.php
+++ b/src/Rules/ModelRuleHelper.php
@@ -13,6 +13,7 @@
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\TypeWithClassName;
 
 final class ModelRuleHelper
 {
@@ -39,7 +40,7 @@ public function findModelReflectionFromType(Type $type): ?ClassReflection
 
         $modelType = TypeCombinator::removeNull($modelType);
 
-        if (! $modelType instanceof ObjectType) {
+        if (! $modelType instanceof TypeWithClassName) {
             return null;
         }
 
diff --git a/src/Rules/OctaneCompatibilityRule.php b/src/Rules/OctaneCompatibilityRule.php
index c75a0e001..0438eb150 100644
--- a/src/Rules/OctaneCompatibilityRule.php
+++ b/src/Rules/OctaneCompatibilityRule.php
@@ -13,6 +13,7 @@
 use PHPStan\Rules\RuleError;
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Type\ObjectType;
+use PHPStan\Type\TypeWithClassName;
 
 /**
  * @implements Rule<MethodCall>
@@ -43,7 +44,7 @@ public function processNode(Node $node, Scope $scope): array
 
         $calledOnType = $scope->getType($node->var);
 
-        if (! $calledOnType instanceof ObjectType) {
+        if (! $calledOnType instanceof TypeWithClassName) {
             return [];
         }
 
diff --git a/src/Rules/RelationExistenceRule.php b/src/Rules/RelationExistenceRule.php
index 02db9221f..173c33548 100644
--- a/src/Rules/RelationExistenceRule.php
+++ b/src/Rules/RelationExistenceRule.php
@@ -72,15 +72,19 @@ public function processNode(Node $node, Scope $scope): array
         $relations = [];
 
         if ($valueType->isConstantArray()->yes()) {
-            $relations = array_merge(
-                $relations,
-                ...array_map(function (Type $type) {
-                    return TypeUtils::getConstantStrings($type);
-                }, $valueType->getKeyTypes()), // @phpstan-ignore-line
-                ...array_map(function (Type $type) {
-                    return TypeUtils::getConstantStrings($type);
-                }, $valueType->getValueTypes()), // @phpstan-ignore-line
-            );
+            $arrays = $valueType->getConstantArrays();
+
+            foreach ($arrays as $array) {
+                $relations = array_merge(
+                    $relations,
+                    ...array_map(function (Type $type) {
+                        return TypeUtils::getConstantStrings($type);
+                    }, $array->getKeyTypes()),
+                    ...array_map(function (Type $type) {
+                        return TypeUtils::getConstantStrings($type);
+                    }, $array->getValueTypes()),
+                );
+            }
         } else {
             $constants = TypeUtils::getConstantStrings($valueType);
 
@@ -153,7 +157,7 @@ public function processNode(Node $node, Scope $scope): array
                 return [];
             }
 
-            $errors += $closure($calledOnType, $relationName, $node);
+            $errors = array_merge($errors, $closure($calledOnType, $relationName, $node));
         }
 
         return $errors;
diff --git a/src/Types/ModelProperty/GenericModelPropertyType.php b/src/Types/ModelProperty/GenericModelPropertyType.php
index 4f561d18d..b797f3855 100644
--- a/src/Types/ModelProperty/GenericModelPropertyType.php
+++ b/src/Types/ModelProperty/GenericModelPropertyType.php
@@ -5,7 +5,6 @@
 namespace NunoMaduro\Larastan\Types\ModelProperty;
 
 use PHPStan\TrinaryLogic;
-use PHPStan\Type\ClassStringType;
 use PHPStan\Type\CompoundType;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\Generic\TemplateType;
@@ -82,7 +81,7 @@ public function inferTemplateTypes(Type $receivedType): TemplateTypeMap
             $typeToInfer = new ObjectType($receivedType->getValue());
         } elseif ($receivedType instanceof self) {
             $typeToInfer = $receivedType->type;
-        } elseif ($receivedType instanceof ClassStringType) {
+        } elseif ($receivedType->isClassStringType()->yes()) {
             $typeToInfer = $this->getGenericType();
 
             if ($typeToInfer instanceof TemplateType) {
diff --git a/src/Types/ModelRelationsDynamicMethodReturnTypeExtension.php b/src/Types/ModelRelationsDynamicMethodReturnTypeExtension.php
index e14e8c11d..ece93a0c6 100644
--- a/src/Types/ModelRelationsDynamicMethodReturnTypeExtension.php
+++ b/src/Types/ModelRelationsDynamicMethodReturnTypeExtension.php
@@ -17,6 +17,7 @@
 use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeWithClassName;
 
 class ModelRelationsDynamicMethodReturnTypeExtension implements DynamicMethodReturnTypeExtension
 {
@@ -41,7 +42,7 @@ public function isMethodSupported(MethodReflection $methodReflection): bool
 
         $returnType = $variants->getReturnType();
 
-        if (! $returnType instanceof ObjectType) {
+        if (! $returnType instanceof TypeWithClassName) {
             return false;
         }
 
diff --git a/src/Types/RelationDynamicMethodReturnTypeExtension.php b/src/Types/RelationDynamicMethodReturnTypeExtension.php
index e0949483d..cab354eaa 100644
--- a/src/Types/RelationDynamicMethodReturnTypeExtension.php
+++ b/src/Types/RelationDynamicMethodReturnTypeExtension.php
@@ -6,7 +6,6 @@
 
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
-use Illuminate\Database\Eloquent\Relations\MorphTo;
 use PhpParser\Node\Expr\MethodCall;
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionVariant;
@@ -20,6 +19,7 @@
 use PHPStan\Type\StaticType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeUtils;
+use PHPStan\Type\TypeWithClassName;
 
 class RelationDynamicMethodReturnTypeExtension implements DynamicMethodReturnTypeExtension
 {
@@ -57,7 +57,7 @@ public function getTypeFromMethodCall(
         $functionVariant = ParametersAcceptorSelector::selectSingle($methodReflection->getVariants());
         $returnType = $functionVariant->getReturnType();
 
-        if (! $returnType instanceof ObjectType) {
+        if (! $returnType instanceof TypeWithClassName) {
             return $returnType;
         }
 
diff --git a/src/Types/RelationParserHelper.php b/src/Types/RelationParserHelper.php
index c487408c9..ff071a616 100644
--- a/src/Types/RelationParserHelper.php
+++ b/src/Types/RelationParserHelper.php
@@ -12,10 +12,10 @@
 use PHPStan\Parser\Parser;
 use PHPStan\Reflection\MethodReflection;
 use PHPStan\Reflection\ReflectionProvider;
-use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\Generic\GenericClassStringType;
 use PHPStan\Type\Generic\TemplateTypeMap;
-use PHPStan\Type\ObjectType;
+use PHPStan\Type\TypeUtils;
+use PHPStan\Type\TypeWithClassName;
 
 class RelationParserHelper
 {
@@ -87,14 +87,16 @@ public function findRelatedModelInRelationMethod(
         $argType = $methodScope->getType($methodCall->getArgs()[0]->value);
         $returnClass = null;
 
-        if ($argType instanceof ConstantStringType) {
-            $returnClass = $argType->getValue();
+        $constantStrings = TypeUtils::getConstantStrings($argType);
+
+        if (count($constantStrings) === 1) {
+            $returnClass = $constantStrings[0]->getValue();
         }
 
         if ($argType instanceof GenericClassStringType) {
             $modelType = $argType->getGenericType();
 
-            if (! $modelType instanceof ObjectType) {
+            if (! $modelType instanceof TypeWithClassName) {
                 return null;
             }
 
diff --git a/tests/Rules/Data/relation-existence-rule.php b/tests/Rules/Data/relation-existence-rule.php
index 48b3c39a7..c4303c1bb 100644
--- a/tests/Rules/Data/relation-existence-rule.php
+++ b/tests/Rules/Data/relation-existence-rule.php
@@ -50,3 +50,6 @@
 \App\User::query()->with('foo:id,name');
 \App\User::with(['foo:id', 'accounts']);
 \App\User::query()->with(['foo:id', 'accounts']);
+
+/** @var array{foo:string}|array{0: 'bar'} $a */
+\App\User::with($a);
diff --git a/tests/Rules/RelationExistenceRuleTest.php b/tests/Rules/RelationExistenceRuleTest.php
index 874156aeb..8d4ec5f15 100644
--- a/tests/Rules/RelationExistenceRuleTest.php
+++ b/tests/Rules/RelationExistenceRuleTest.php
@@ -184,11 +184,18 @@ public function testRule(): void
                 'Relation \'foo\' is not found in App\User model.',
                 51,
             ],
-
             [
                 'Relation \'foo\' is not found in App\User model.',
                 52,
             ],
+            [
+                'Relation \'foo\' is not found in App\User model.',
+                55,
+            ],
+            [
+                'Relation \'bar\' is not found in App\User model.',
+                55,
+            ],
         ]);
     }