date: promote before multiply
diff --git a/src/date.c b/src/date.c
index 71bf631..2297ee6 100644
--- a/src/date.c
+++ b/src/date.c
@@ -722,7 +722,7 @@ static const char *approxidate_alpha(const char *date, struct tm *tm, struct tm
while (tl->type) {
size_t len = strlen(tl->type);
if (match_string(date, tl->type) >= len-1) {
- update_tm(tm, now, tl->length * *num);
+ update_tm(tm, now, tl->length * (unsigned long)*num);
*num = 0;
*touched = 1;
return end;