diff --git a/cache.h b/cache.h
index 34c33e6a28..fe00ddf910 100644
--- a/cache.h
+++ b/cache.h
@@ -1467,6 +1467,8 @@ struct date_mode *date_mode_from_type(enum date_mode_type type);
 const char *show_date(timestamp_t time, int timezone, const struct date_mode *mode);
 void show_date_relative(timestamp_t time, int tz, const struct timeval *now,
 			struct strbuf *timebuf);
+void show_date_human(timestamp_t time, int tz, const struct timeval *now,
+			struct strbuf *timebuf);
 int parse_date(const char *date, struct strbuf *out);
 int parse_date_basic(const char *date, timestamp_t *timestamp, int *offset);
 int parse_expiry_date(const char *date, timestamp_t *timestamp);
diff --git a/date.c b/date.c
index 43c3a84e25..e997664c1a 100644
--- a/date.c
+++ b/date.c
@@ -115,6 +115,19 @@ static int local_tzoffset(timestamp_t time)
 	return local_time_tzoffset((time_t)time, &tm);
 }
 
+static void get_time(struct timeval *now)
+{
+	const char *x;
+
+	x = getenv("GIT_TEST_DATE_NOW");
+	if (x) {
+		now->tv_sec = atoi(x);
+		now->tv_usec = 0;
+	}
+	else
+		gettimeofday(now, NULL);
+}
+
 void show_date_relative(timestamp_t time, int tz,
 			       const struct timeval *now,
 			       struct strbuf *timebuf)
@@ -228,7 +241,7 @@ static void show_date_normal(struct strbuf *buf, timestamp_t time, struct tm *tm
 	/* Show "today" times as just relative times */
 	if (hide.wday) {
 		struct timeval now;
-		gettimeofday(&now, NULL);
+		get_time(&now);
 		show_date_relative(time, tz, &now, buf);
 		return;
 	}
@@ -284,7 +297,7 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
 	if (mode->type == DATE_HUMAN) {
 		struct timeval now;
 
-		gettimeofday(&now, NULL);
+		get_time(&now);
 
 		/* Fill in the data for "current time" in human_tz and human_tm */
 		human_tz = local_time_tzoffset(now.tv_sec, &human_tm);
@@ -303,7 +316,7 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
 		struct timeval now;
 
 		strbuf_reset(&timebuf);
-		gettimeofday(&now, NULL);
+		get_time(&now);
 		show_date_relative(time, tz, &now, &timebuf);
 		return timebuf.buf;
 	}
@@ -1296,7 +1309,7 @@ timestamp_t approxidate_careful(const char *date, int *error_ret)
 		return timestamp;
 	}
 
-	gettimeofday(&tv, NULL);
+	get_time(&tv);
 	return approxidate_str(date, &tv, error_ret);
 }
 
diff --git a/t/helper/test-date.c b/t/helper/test-date.c
index a0837371ab..9b2ac772ee 100644
--- a/t/helper/test-date.c
+++ b/t/helper/test-date.c
@@ -3,6 +3,7 @@
 
 static const char *usage_msg = "\n"
 "  test-tool date relative [time_t]...\n"
+"  test-tool date human [time_t]...\n"
 "  test-tool date show:<format> [time_t]...\n"
 "  test-tool date parse [date]...\n"
 "  test-tool date approxidate [date]...\n"
@@ -22,6 +23,14 @@ static void show_relative_dates(const char **argv, struct timeval *now)
 	strbuf_release(&buf);
 }
 
+static void show_human_dates(const char **argv)
+{
+	for (; *argv; argv++) {
+		time_t t = atoi(*argv);
+		printf("%s -> %s\n", *argv, show_date(t, 0, DATE_MODE(HUMAN)));
+	}
+}
+
 static void show_dates(const char **argv, const char *format)
 {
 	struct date_mode mode;
@@ -87,7 +96,7 @@ int cmd__date(int argc, const char **argv)
 	struct timeval now;
 	const char *x;
 
-	x = getenv("TEST_DATE_NOW");
+	x = getenv("GIT_TEST_DATE_NOW");
 	if (x) {
 		now.tv_sec = atoi(x);
 		now.tv_usec = 0;
@@ -100,6 +109,8 @@ int cmd__date(int argc, const char **argv)
 		usage(usage_msg);
 	if (!strcmp(*argv, "relative"))
 		show_relative_dates(argv+1, &now);
+	else if (!strcmp(*argv, "human"))
+		show_human_dates(argv+1);
 	else if (skip_prefix(*argv, "show:", &x))
 		show_dates(argv+1, x);
 	else if (!strcmp(*argv, "parse"))
diff --git a/t/t0006-date.sh b/t/t0006-date.sh
index ffb2975e48..90930c2aa7 100755
--- a/t/t0006-date.sh
+++ b/t/t0006-date.sh
@@ -4,10 +4,10 @@ test_description='test date parsing and printing'
 . ./test-lib.sh
 
 # arbitrary reference time: 2009-08-30 19:20:00
-TEST_DATE_NOW=1251660000; export TEST_DATE_NOW
+GIT_TEST_DATE_NOW=1251660000; export GIT_TEST_DATE_NOW
 
 check_relative() {
-	t=$(($TEST_DATE_NOW - $1))
+	t=$(($GIT_TEST_DATE_NOW - $1))
 	echo "$t -> $2" >expect
 	test_expect_${3:-success} "relative date ($2)" "
 	test-tool date relative $t >actual &&
