diff --git a/lib/parse-date.y b/lib/parse-date.y
index 5e966f0c3..bb5abb5d4 100644
--- a/lib/parse-date.y
+++ b/lib/parse-date.y
@@ -1503,7 +1503,7 @@ int parse_date(struct timespec *result, char const *p,
 
 				if (!tz_was_altered)
 					tz0 = get_tz (tz0buf);
-				sprintf (tz1buf, "XXX%s%ld:%02d",
+				sprintf (tz1buf, "XXX%s%jd:%02d",
 					 &"-"[time_zone < 0],
 					 abs_time_zone_hour,
 					 abs_time_zone_min);