diff --git a/date.c b/date.c
index 68cdcaa3f6..3c981f7eb5 100644
--- a/date.c
+++ b/date.c
@@ -635,7 +635,7 @@ int parse_date_toffset(const char *date, unsigned long *timestamp, int *offset)
 	/* mktime uses local timezone */
 	*timestamp = tm_to_time_t(&tm);
 	if (*offset == -1)
-		*offset = (*timestamp - mktime(&tm)) / 60;
+		*offset = ((time_t)*timestamp - mktime(&tm)) / 60;
 
 	if (*timestamp == -1)
 		return -1;
diff --git a/t/t0006-date.sh b/t/t0006-date.sh
index 3ea4f9eff9..b2df4fe102 100755
--- a/t/t0006-date.sh
+++ b/t/t0006-date.sh
@@ -39,6 +39,7 @@ check_parse 2008-02 bad
 check_parse 2008-02-14 bad
 check_parse '2008-02-14 20:30:45' '2008-02-14 20:30:45 +0000'
 check_parse '2008-02-14 20:30:45 -0500' '2008-02-14 20:30:45 -0500'
+check_parse '2008-02-14 20:30:45' '2008-02-14 20:30:45 -0500' EST
 
 check_approxidate() {
 	echo "$1 -> $2 +0000" >expect