diff --git a/packages/NodeCollector/NodeCollector/NodeRepository.php b/packages/NodeCollector/NodeCollector/NodeRepository.php
index d5f05a95c30..82cf68fcf67 100644
--- a/packages/NodeCollector/NodeCollector/NodeRepository.php
+++ b/packages/NodeCollector/NodeCollector/NodeRepository.php
@@ -471,7 +471,7 @@ private function collectArray(Array_ $array): void
             return;
         }
 
-        $this->arrayCallablesByTypeAndMethod[$arrayCallable->getClass()][$arrayCallable->getMethod()][] = $arrayCallable;
+        $this->arrayCallablesByTypeAndMethod[$arrayCallable->getClass()][strtolower($arrayCallable->getMethod())][] = $arrayCallable;
     }
 
     private function addMethod(ClassMethod $classMethod): void
diff --git a/rules-tests/DeadCode/Rector/ClassMethod/RemoveUnusedPrivateMethodRector/Fixture/skip_array_callables_this_case_insensitive_method_name.php.inc b/rules-tests/DeadCode/Rector/ClassMethod/RemoveUnusedPrivateMethodRector/Fixture/skip_array_callables_this_case_insensitive_method_name.php.inc
new file mode 100644
index 00000000000..5222b048533
--- /dev/null
+++ b/rules-tests/DeadCode/Rector/ClassMethod/RemoveUnusedPrivateMethodRector/Fixture/skip_array_callables_this_case_insensitive_method_name.php.inc
@@ -0,0 +1,26 @@
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\ClassMethod\RemoveUnusedPrivateMethodRector\Fixture;
+
+final class SkipArrayCallablesThisCaseInsensitiveMethodName
+{
+    public function run()
+    {
+        $array  = [3, 2, 1];
+
+        usort($array, [$this, 'sortCamelCasedMethodName']);
+        usort($array, [$this, 'sortCaseInSensitiveMETHODName']);
+
+        return $array;
+    }
+
+    private function sortCamelCasedMethodName($a, $b)
+    {
+        return $a <=> $b;
+    }
+
+    private function SOrtCAseINSENsitivEMEthodnaME($a, $b)
+    {
+        return $a <=> $b;
+    }
+}