diff --git a/bin/mailsync b/bin/mailsync
index f0b62ea..f7c3211 100755
--- a/bin/mailsync
+++ b/bin/mailsync
@@ -58,7 +58,7 @@ done
 
 wait
 rm -f /tmp/imapsyncicon_"$USER"
-pkill -RTMIN+12 "$STATUSBAR" >/dev/null 2>&1
+pkill -RTMIN+12 "${STATUSBAR:?}" >/dev/null 2>&1
 
 notmuch new 2>/dev/null