diff --git a/td/telegram/net/NetQuery.cpp b/td/telegram/net/NetQuery.cpp
index 90ad2a8d5..08ca507ab 100644
--- a/td/telegram/net/NetQuery.cpp
+++ b/td/telegram/net/NetQuery.cpp
@@ -63,6 +63,10 @@ void NetQuery::set_error(Status status, string source) {
 }
 
 TsList<NetQueryDebug> &NetQuery::get_net_query_list() {
+  static auto init_mutex = [] {
+    TsList<NetQueryDebug>::lock().unlock();  // initialize mutex before any NetQuery
+    return true;
+  };
   static TsList<NetQueryDebug> net_query_list;
   return net_query_list;
 }