diff --git a/CryptCommandListener.cpp b/CryptCommandListener.cpp
index 93f953f..5de5cf2 100644
--- a/CryptCommandListener.cpp
+++ b/CryptCommandListener.cpp
@@ -366,8 +366,11 @@
 
     } else if (subcommand == "prepare_user_storage") {
         CHECK_ARGC(6, "prepare_user_storage <uuid> <user> <serial> <ephemeral>");
-        return sendGenericOkFail(cli, e4crypt_prepare_user_storage(
-                parseNull(argv[2]), atoi(argv[3]), atoi(argv[4]) != 0));
+        return sendGenericOkFail(cli,
+                                 e4crypt_prepare_user_storage(parseNull(argv[2]),
+                                                              atoi(argv[3]),
+                                                              atoi(argv[4]),
+                                                              atoi(argv[5]) != 0));
 
     } else {
         dumpArgs(argc, argv, -1);
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));
diff --git a/Ext4Crypt.h b/Ext4Crypt.h
index a3d9224..eb33876 100644
--- a/Ext4Crypt.h
+++ b/Ext4Crypt.h
@@ -44,6 +44,9 @@
 int e4crypt_unlock_user_key(userid_t user_id, const char* token);
 int e4crypt_lock_user_key(userid_t user_id);
 
-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);
 
 __END_DECLS
diff --git a/main.cpp b/main.cpp
index ea374c5..91e2d98 100644
--- a/main.cpp
+++ b/main.cpp
@@ -98,7 +98,7 @@
     }
 
     // Prepare owner storage
-    e4crypt_prepare_user_storage(nullptr, 0, false);
+    e4crypt_prepare_user_storage(nullptr, 0, 0, false);
 
     cl = new CommandListener();
     ccl = new CryptCommandListener();