diff --git a/build/gen_stub.php b/build/gen_stub.php
index 94eab3be1ef..6856b5610e9 100755
--- a/build/gen_stub.php
+++ b/build/gen_stub.php
@@ -1756,7 +1756,7 @@ class ClassInfo {
         }
 
         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) {