diff --git a/build/gen_stub.php b/build/gen_stub.php
index 486ff679499fc..348cc9e82d277 100755
--- a/build/gen_stub.php
+++ b/build/gen_stub.php
@@ -1748,7 +1748,7 @@ function (Name $item) {
         }
 
         if ($this->alias) {
-            $code .= "\tzend_register_class_alias(\"" . str_replace("\\", "_", $this->alias) . "\", class_entry);\n";
+            $code .= "\tzend_register_class_alias(\"" . str_replace("\\", "\\\\", $this->alias) . "\", class_entry);\n";
         }
 
         foreach ($this->enumCaseInfos as $enumCase) {