diff --git a/main/was.c b/main/was.c
index 0d9733dc..b397fd5a 100644
--- a/main/was.c
+++ b/main/was.c
@@ -36,7 +36,7 @@ struct notify_data {
     char *audio_url;
     bool backlight;
     bool backlight_max;
-    bool cancel;
+    _Atomic bool cancel;
     char *text;
     int repeat;
     int strobe_period_ms;