diff --git a/builtin/grep.c b/builtin/grep.c
index 50ce8d9461..896e7effce 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -407,8 +407,7 @@ static int grep_submodule(struct grep_opt *opt,
 {
 	struct repository subrepo;
 	struct repository *superproject = opt->repo;
-	const struct submodule *sub = submodule_from_path(superproject,
-							  &null_oid, path);
+	const struct submodule *sub;
 	struct grep_opt subopt;
 	int hit;
 
@@ -419,6 +418,7 @@ static int grep_submodule(struct grep_opt *opt,
 	 * object.
 	 */
 	grep_read_lock();
+	sub = submodule_from_path(superproject, &null_oid, path);
 
 	if (!is_submodule_active(superproject, path)) {
 		grep_read_unlock();
@@ -455,9 +455,8 @@ static int grep_submodule(struct grep_opt *opt,
 		unsigned long size;
 		struct strbuf base = STRBUF_INIT;
 
-		object = parse_object_or_die(oid, oid_to_hex(oid));
-
 		grep_read_lock();
+		object = parse_object_or_die(oid, oid_to_hex(oid));
 		data = read_object_with_reference(&subrepo,
 						  &object->oid, tree_type,
 						  &size, NULL);