diff --git a/storaged/include/storaged.h b/storaged/include/storaged.h
index 6f92048..79b5d41 100644
--- a/storaged/include/storaged.h
+++ b/storaged/include/storaged.h
@@ -86,6 +86,7 @@
     sp<android::hardware::health::V2_0::IHealth> health;
     unique_ptr<storage_info_t> storage_info;
     static const uint32_t current_version;
+    Mutex proto_lock;
     unordered_map<userid_t, bool> proto_loaded;
     void load_proto(userid_t user_id);
     char* prepare_proto(userid_t user_id, StoragedProto* proto);
diff --git a/storaged/storaged.cpp b/storaged/storaged.cpp
index 1d934a2..3e0f70d 100644
--- a/storaged/storaged.cpp
+++ b/storaged/storaged.cpp
@@ -164,6 +164,8 @@
 }
 
 void storaged_t::add_user_ce(userid_t user_id) {
+    Mutex::Autolock _l(proto_lock);
+
     if (!proto_loaded[user_id]) {
         load_proto(user_id);
         proto_loaded[user_id] = true;
@@ -171,6 +173,8 @@
 }
 
 void storaged_t::remove_user_ce(userid_t user_id) {
+    Mutex::Autolock _l(proto_lock);
+
     proto_loaded[user_id] = false;
     mUidm.clear_user_history(user_id);
     RemoveFileIfExists(proto_path(user_id), nullptr);
@@ -301,6 +305,8 @@
 }
 
 void storaged_t::flush_protos(unordered_map<int, StoragedProto>* protos) {
+    Mutex::Autolock _l(proto_lock);
+
     for (auto& it : *protos) {
         /*
          * Don't flush proto if we haven't attempted to load it from file.