diff --git a/Ext4Crypt.cpp b/Ext4Crypt.cpp
index 38dc27d..c3dcd0d 100644
--- a/Ext4Crypt.cpp
+++ b/Ext4Crypt.cpp
@@ -753,7 +753,10 @@
     return 0;
 }
 
-int e4crypt_prepare_user_storage(const char* volume_uuid, userid_t user_id, bool ephemeral) {
+int e4crypt_prepare_user_storage(const char* volume_uuid,
+                                 userid_t user_id,
+                                 int serial,
+                                 bool ephemeral) {
     std::string system_ce_path(android::vold::BuildDataSystemCePath(user_id));
     std::string user_ce_path(android::vold::BuildDataUserPath(volume_uuid, user_id));
     std::string user_de_path(android::vold::BuildDataUserDePath(volume_uuid, user_id));