diff --git a/t/helper/test-submodule.c b/t/helper/test-submodule.c
index 9adbc8d1568f82..7197969a081496 100644
--- a/t/helper/test-submodule.c
+++ b/t/helper/test-submodule.c
@@ -15,6 +15,13 @@ static const char *submodule_check_name_usage[] = {
 	NULL
 };
 
+#define TEST_TOOL_CHECK_URL_USAGE \
+	"test-tool submodule check-url"
+static const char *submodule_check_url_usage[] = {
+	TEST_TOOL_CHECK_URL_USAGE,
+	NULL
+};
+
 #define TEST_TOOL_IS_ACTIVE_USAGE \
 	"test-tool submodule is-active <name>"
 static const char *submodule_is_active_usage[] = {
@@ -31,17 +38,23 @@ static const char *submodule_resolve_relative_url_usage[] = {
 
 static const char *submodule_usage[] = {
 	TEST_TOOL_CHECK_NAME_USAGE,
+	TEST_TOOL_CHECK_URL_USAGE,
 	TEST_TOOL_IS_ACTIVE_USAGE,
 	TEST_TOOL_RESOLVE_RELATIVE_URL_USAGE,
 	NULL
 };
 
-/* Filter stdin to print only valid names. */
-static int check_name(void)
+typedef int (*check_fn_t)(const char *);
+
+/*
+ * Apply 'check_fn' to each line of stdin, printing values that pass the check
+ * to stdout.
+ */
+static int check_submodule(check_fn_t check_fn)
 {
 	struct strbuf buf = STRBUF_INIT;
 	while (strbuf_getline(&buf, stdin) != EOF) {
-		if (!check_submodule_name(buf.buf))
+		if (!check_fn(buf.buf))
 			printf("%s\n", buf.buf);
 	}
 	strbuf_release(&buf);
@@ -58,7 +71,20 @@ static int cmd__submodule_check_name(int argc, const char **argv)
 	if (argc)
 		usage_with_options(submodule_check_name_usage, options);
 
-	return check_name();
+	return check_submodule(check_submodule_name);
+}
+
+static int cmd__submodule_check_url(int argc, const char **argv)
+{
+	struct option options[] = {
+		OPT_END()
+	};
+	argc = parse_options(argc, argv, "test-tools", options,
+			     submodule_check_url_usage, 0);
+	if (argc)
+		usage_with_options(submodule_check_url_usage, options);
+
+	return check_submodule(check_submodule_url);
 }
 
 static int cmd__submodule_is_active(int argc, const char **argv)
@@ -184,6 +210,7 @@ static int cmd__submodule_config_writeable(int argc, const char **argv UNUSED)
 
 static struct test_cmd cmds[] = {
 	{ "check-name", cmd__submodule_check_name },
+	{ "check-url", cmd__submodule_check_url },
 	{ "is-active", cmd__submodule_is_active },
 	{ "resolve-relative-url", cmd__submodule_resolve_relative_url},
 	{ "config-list", cmd__submodule_config_list },
diff --git a/t/t7450-bad-git-dotfiles.sh b/t/t7450-bad-git-dotfiles.sh
index 35a31acd4d7e26..c73b1c92ecca7c 100755
--- a/t/t7450-bad-git-dotfiles.sh
+++ b/t/t7450-bad-git-dotfiles.sh
@@ -45,6 +45,41 @@ test_expect_success 'check names' '
 	test_cmp expect actual
 '
 
+test_expect_success 'check urls' '
+	cat >expect <<-\EOF &&
+	./bar/baz/foo.git
+	https://example.com/foo.git
+	http://example.com:80/deeper/foo.git
+	EOF
+
+	test-tool submodule check-url >actual <<-\EOF &&
+	./bar/baz/foo.git
+	https://example.com/foo.git
+	http://example.com:80/deeper/foo.git
+	-a./foo
+	../../..//test/foo.git
+	../../../../../:localhost:8080/foo.git
+	..\../.\../:example.com/foo.git
+	./%0ahost=example.com/foo.git
+	https://one.example.com/evil?%0ahost=two.example.com
+	https:///example.com/foo.git
+	https::example.com/foo.git
+	http:::example.com/foo.git
+	EOF
+
+	test_cmp expect actual
+'
+
+# NEEDSWORK: the URL checked here is not valid (and will not work as a remote if
+# a user attempts to clone it), but the fsck check passes.
+test_expect_failure 'url check misses invalid cases' '
+	test-tool submodule check-url >actual <<-\EOF &&
+	http://example.com:test/foo.git
+	EOF
+
+	test_must_be_empty actual
+'
+
 test_expect_success 'create innocent subrepo' '
 	git init innocent &&
 	git -C innocent commit --allow-empty -m foo