diff --git a/rules-tests/TypeDeclaration/Rector/ClassMethod/AddVoidReturnTypeWhereNoReturnRector/Fixture/some_function.php.inc b/rules-tests/TypeDeclaration/Rector/ClassMethod/AddVoidReturnTypeWhereNoReturnRector/Fixture/some_function.php.inc
new file mode 100644
index 00000000000..ed413fe5b16
--- /dev/null
+++ b/rules-tests/TypeDeclaration/Rector/ClassMethod/AddVoidReturnTypeWhereNoReturnRector/Fixture/some_function.php.inc
@@ -0,0 +1,19 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\ClassMethod\AddVoidReturnTypeWhereNoReturnRector\Fixture;
+
+function some_function()
+{
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\ClassMethod\AddVoidReturnTypeWhereNoReturnRector\Fixture;
+
+function some_function(): void
+{
+}
+
+?>
diff --git a/rules/TypeDeclaration/TypeInferer/SilentVoidResolver.php b/rules/TypeDeclaration/TypeInferer/SilentVoidResolver.php
index cd93e20cf26..508148b1348 100644
--- a/rules/TypeDeclaration/TypeInferer/SilentVoidResolver.php
+++ b/rules/TypeDeclaration/TypeInferer/SilentVoidResolver.php
@@ -48,7 +48,7 @@ public function hasExclusiveVoid(ClassMethod | Closure | Function_ $functionLike
             return false;
         }
 
-        if ($this->externalFullyQualifiedAnalyzer->hasExternalFullyQualifieds($classLike)) {
+        if ($classLike instanceof Stmt\Class_ && $this->externalFullyQualifiedAnalyzer->hasExternalFullyQualifieds($classLike)) {
             return false;
         }