diff --git a/config.c b/config.c
index 9a5c5470cc..80db92990a 100644
--- a/config.c
+++ b/config.c
@@ -234,17 +234,23 @@ static int git_parse_file(config_fn_t fn)
 	die("bad config file line %d in %s", config_linenr, config_file_name);
 }
 
-static unsigned long get_unit_factor(const char *end)
+static int parse_unit_factor(const char *end, unsigned long *val)
 {
 	if (!*end)
 		return 1;
-	else if (!strcasecmp(end, "k"))
-		return 1024;
-	else if (!strcasecmp(end, "m"))
-		return 1024 * 1024;
-	else if (!strcasecmp(end, "g"))
-		return 1024 * 1024 * 1024;
-	die("unknown unit: '%s'", end);
+	else if (!strcasecmp(end, "k")) {
+		*val *= 1024;
+		return 1;
+	}
+	else if (!strcasecmp(end, "m")) {
+		*val *= 1024 * 1024;
+		return 1;
+	}
+	else if (!strcasecmp(end, "g")) {
+		*val *= 1024 * 1024 * 1024;
+		return 1;
+	}
+	return 0;
 }
 
 int git_parse_long(const char *value, long *ret)
@@ -252,7 +258,10 @@ int git_parse_long(const char *value, long *ret)
 	if (value && *value) {
 		char *end;
 		long val = strtol(value, &end, 0);
-		*ret = val * get_unit_factor(end);
+		unsigned long factor = 1;
+		if (!parse_unit_factor(end, &factor))
+			return 0;
+		*ret = val * factor;
 		return 1;
 	}
 	return 0;
@@ -263,7 +272,9 @@ int git_parse_ulong(const char *value, unsigned long *ret)
 	if (value && *value) {
 		char *end;
 		unsigned long val = strtoul(value, &end, 0);
-		*ret = val * get_unit_factor(end);
+		if (!parse_unit_factor(end, &val))
+			return 0;
+		*ret = val;
 		return 1;
 	}
 	return 0;
diff --git a/t/t1300-repo-config.sh b/t/t1300-repo-config.sh
index e894629e7e..42eac2a7cb 100755
--- a/t/t1300-repo-config.sh
+++ b/t/t1300-repo-config.sh
@@ -448,6 +448,23 @@ test_expect_success numbers '
 	test z1048576 = "z$m"
 '
 
+cat > expect <<EOF
+fatal: bad config value for 'aninvalid.unit' in .git/config
+EOF
+
+test_expect_success 'invalid unit' '
+
+	git config aninvalid.unit "1auto" &&
+	s=$(git config aninvalid.unit) &&
+	test "z1auto" = "z$s" &&
+	if git config --int --get aninvalid.unit 2>actual
+	then
+		echo config should have failed
+		false
+	fi &&
+	cmp actual expect
+'
+
 cat > expect << EOF
 true
 false