diff --git a/gdb/complaints.c b/gdb/complaints.c
index 4a2318a7f80..ab6e2049685 100644
--- a/gdb/complaints.c
+++ b/gdb/complaints.c
@@ -71,6 +71,7 @@ complaint_internal (const char *fmt, ...)
 void
 clear_complaints ()
 {
+  gdb::lock_guard<gdb::mutex> guard (complaint_mutex);
   counters.clear ();
 }