diff --git a/src/CodeCleaner/ReturnTypePass.php b/src/CodeCleaner/ReturnTypePass.php
index 5d718cdb..29b69895 100644
--- a/src/CodeCleaner/ReturnTypePass.php
+++ b/src/CodeCleaner/ReturnTypePass.php
@@ -105,10 +105,14 @@ private function typeName(Node $node): string
             return \strtolower($node->type->name);
         }
 
-        if ($node instanceof Identifier || $node instanceof Name) {
+        if ($node instanceof Identifier) {
             return \strtolower($node->name);
         }
 
+        if ($node instanceof Name) {
+            return $node->toLowerString();
+        }
+
         throw new \InvalidArgumentException('Unable to find type name');
     }
 }