diff --git a/source/librpc/idl/winreg.idl b/source/librpc/idl/winreg.idl
index f7a61ecbead..2183a2cb2d4 100644
--- a/source/librpc/idl/winreg.idl
+++ b/source/librpc/idl/winreg.idl
@@ -242,7 +242,7 @@ import "lsa.idl", "initshutdown.idl", "security.idl";
 	/* Function: 0x11 */
 	WERROR winreg_QueryValue(
 		[in,ref] policy_handle *handle,
-		[in] winreg_String value_name,
+		[in,ref] winreg_String *value_name,
 		[in,out,unique] winreg_Type *type,
 		[in,out,unique,size_is(*data_size),length_is(*value_length)] uint8 *data,
 		[in,out,unique] uint32 *data_size,