1 files changed, 4 insertions, 1 deletions

diff --git a/tools/perf/util/ui/helpline.c b/tools/perf/util/ui/helpline.c
index 8d79daa4458a..f36d2ff509ed 100644
--- a/tools/perf/util/ui/helpline.c
+++ b/tools/perf/util/ui/helpline.c
@@ -5,6 +5,7 @@
 
 #include "../debug.h"
 #include "helpline.h"
+#include "ui.h"
 
 void ui_helpline__pop(void)
 {
@@ -55,7 +56,8 @@ int ui_helpline__show_help(const char *format, va_list ap)
         int ret;
         static int backlog;
 
-        ret = vsnprintf(ui_helpline__last_msg + backlog,
+        pthread_mutex_lock(&ui__lock);
+        ret = vsnprintf(ui_helpline__last_msg + backlog,
                         sizeof(ui_helpline__last_msg) - backlog, format, ap);
         backlog += ret;
 
@@ -64,6 +66,7 @@ int ui_helpline__show_help(const char *format, va_list ap)
                 newtRefresh();
                 backlog = 0;
         }
+        pthread_mutex_unlock(&ui__lock);
 
         return ret;
 }