diff --git a/builtin/config.c b/builtin/config.c
index 5677c942b6..8224699663 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -599,7 +599,7 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		check_argc(argc, 2, 2);
 		value = normalize_value(argv[0], argv[1]);
 		return git_config_set_multivar_in_file(given_config_source.file,
-						       argv[0], value, "^$", 0);
+						       argv[0], value, "a^", 0);
 	}
 	else if (actions == ACTION_REPLACE_ALL) {
 		check_write();
diff --git a/config.c b/config.c
index 2634457f6b..ffe010423d 100644
--- a/config.c
+++ b/config.c
@@ -1233,7 +1233,7 @@ static int matches(const char *key, const char *value)
 	return !strcmp(key, store.key) &&
 		(store.value_regex == NULL ||
 		 (store.do_not_match ^
-		  !regexec(store.value_regex, value, 0, NULL, 0)));
+		  (value && !regexec(store.value_regex, value, 0, NULL, 0))));
 }
 
 static int store_aux(const char *key, const char *value, void *cb)
diff --git a/t/t1303-wacky-config.sh b/t/t1303-wacky-config.sh
index 3a2c81968c..3b92083e19 100755
--- a/t/t1303-wacky-config.sh
+++ b/t/t1303-wacky-config.sh
@@ -111,4 +111,24 @@ test_expect_success 'unset many entries' '
 	test_must_fail git config section.key
 '
 
+test_expect_success '--add appends new value after existing empty value' '
+	cat >expect <<-\EOF &&
+
+
+	fool
+	roll
+	EOF
+	cp .git/config .git/config.old &&
+	test_when_finished "mv .git/config.old .git/config" &&
+	cat >.git/config <<-\EOF &&
+	[foo]
+		baz
+		baz =
+		baz = fool
+	EOF
+	git config --add foo.baz roll &&
+	git config --get-all foo.baz >output &&
+	test_cmp expect output
+'
+
 test_done