diff --git a/rules-tests/TypeDeclaration/Rector/FuncCall/AddArrowFunctionParamArrayWhereDimFetchRector/Fixture/skip_integer_index_on_string.php.inc b/rules-tests/TypeDeclaration/Rector/FuncCall/AddArrowFunctionParamArrayWhereDimFetchRector/Fixture/skip_integer_index_on_string.php.inc
new file mode 100644
index 00000000000..1846fac2c0d
--- /dev/null
+++ b/rules-tests/TypeDeclaration/Rector/FuncCall/AddArrowFunctionParamArrayWhereDimFetchRector/Fixture/skip_integer_index_on_string.php.inc
@@ -0,0 +1,19 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FuncCall\AddArrowFunctionParamArrayWhereDimFetchRector\Fixture;
+
+final class SkipIntegerIndexOnString
+{
+    public function run()
+    {
+        $username = 'john.doe';
+
+        $initials = implode(
+            '',
+            array_map(
+                static fn ($name): string => strtoupper((string) $name[0]),
+                explode('.', $username),
+            ),
+        );
+    }
+}
diff --git a/rules/TypeDeclaration/Rector/FuncCall/AddArrowFunctionParamArrayWhereDimFetchRector.php b/rules/TypeDeclaration/Rector/FuncCall/AddArrowFunctionParamArrayWhereDimFetchRector.php
index 9e404ea0acc..7d04f95de39 100644
--- a/rules/TypeDeclaration/Rector/FuncCall/AddArrowFunctionParamArrayWhereDimFetchRector.php
+++ b/rules/TypeDeclaration/Rector/FuncCall/AddArrowFunctionParamArrayWhereDimFetchRector.php
@@ -146,6 +146,12 @@ private function resolveDimFetchVariableNames(Closure|ArrowFunction $closureExpr
 
         foreach ($arrayDimFetches as $arrayDimFetch) {
             if ($arrayDimFetch->var instanceof Variable) {
+                $type = $this->nodeTypeResolver->getNativeType($arrayDimFetch->var);
+
+                if ($type->isString()->yes()) {
+                    continue;
+                }
+
                 $usedDimFetchVariableNames[] = (string) $this->getName($arrayDimFetch->var);
             }
         }