diff --git a/src/proto_http.c b/src/proto_http.c
index 5db64b5..02dc42b 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -11249,6 +11249,8 @@
 		curr_date += args[0].data.sint;
 
 	tm = gmtime(&curr_date);
+	if (!tm)
+		return 0;
 
 	temp = get_trash_chunk();
 	temp->len = snprintf(temp->str, temp->size - temp->len,