diff --git a/src/Tokenizer/Transformer/TypeAlternationTransformer.php b/src/Tokenizer/Transformer/TypeAlternationTransformer.php
index 07cd08879b7..747d6389cba 100644
--- a/src/Tokenizer/Transformer/TypeAlternationTransformer.php
+++ b/src/Tokenizer/Transformer/TypeAlternationTransformer.php
@@ -18,7 +18,8 @@
 use PhpCsFixer\Tokenizer\Tokens;
 
 /**
- * Transform `|` operator into CT::T_TYPE_ALTERNATION in `} catch (ExceptionType1 | ExceptionType2 $e) {`.
+ * Transform `|` operator into CT::T_TYPE_ALTERNATION in `function foo(Type1 | Type2 $x) {`
+ *                                                    or `} catch (ExceptionType1 | ExceptionType2 $e) {`.
  *
  * @author Dariusz Rumiński <dariusz.ruminski@gmail.com>
  *
@@ -31,7 +32,7 @@ final class TypeAlternationTransformer extends AbstractTransformer
      */
     public function getPriority()
     {
-        // needs to run after TypeColonTransformer
+        // needs to run after ArrayTypehintTransformer and TypeColonTransformer
         return -15;
     }
 
@@ -54,7 +55,7 @@ public function process(Tokens $tokens, Token $token, $index)
 
         $prevIndex = $tokens->getPrevMeaningfulToken($index);
 
-        if (!$tokens[$prevIndex]->isGivenKind(T_STRING)) {
+        if (!$tokens[$prevIndex]->isGivenKind([T_STRING, CT::T_ARRAY_TYPEHINT])) {
             return;
         }
 
diff --git a/tests/Fixer/ClassNotation/VisibilityRequiredFixerTest.php b/tests/Fixer/ClassNotation/VisibilityRequiredFixerTest.php
index ae9ca1defe2..99b3a5eb99e 100644
--- a/tests/Fixer/ClassNotation/VisibilityRequiredFixerTest.php
+++ b/tests/Fixer/ClassNotation/VisibilityRequiredFixerTest.php
@@ -849,5 +849,18 @@ public function provideFix80Cases()
         yield [
             '<?php class Foo { private int | /* or empty */ null $foo; }',
         ];
+
+        yield [
+            '<?php class Foo { private array|null $foo; }',
+        ];
+
+        yield [
+            '<?php class Foo { private null|array $foo; }',
+        ];
+
+        yield [
+            '<?php class Foo { public static null|array $foo; }',
+            '<?php class Foo { static null|array $foo; }',
+        ];
     }
 }
diff --git a/tests/Tokenizer/Transformer/TypeAlternationTransformerTest.php b/tests/Tokenizer/Transformer/TypeAlternationTransformerTest.php
index c009ebd2612..d6dcc4cc1b3 100644
--- a/tests/Tokenizer/Transformer/TypeAlternationTransformerTest.php
+++ b/tests/Tokenizer/Transformer/TypeAlternationTransformerTest.php
@@ -226,5 +226,29 @@ class Foo {
                 35 => CT::T_TYPE_ALTERNATION,
             ],
         ];
+
+        yield 'array as first element of types' => [
+            '<?php function foo(array|bool|null $foo) {}',
+            [
+                6 => CT::T_TYPE_ALTERNATION,
+                8 => CT::T_TYPE_ALTERNATION,
+            ],
+        ];
+
+        yield 'array as middle element of types' => [
+            '<?php function foo(null|array|bool $foo) {}',
+            [
+                6 => CT::T_TYPE_ALTERNATION,
+                8 => CT::T_TYPE_ALTERNATION,
+            ],
+        ];
+
+        yield 'array as last element of types' => [
+            '<?php function foo(null|bool|array $foo) {}',
+            [
+                6 => CT::T_TYPE_ALTERNATION,
+                8 => CT::T_TYPE_ALTERNATION,
+            ],
+        ];
     }
 }