diff --git a/builtin/grep.c b/builtin/grep.c
index 7d2f8e5adb..87bcb934a2 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -450,7 +450,7 @@ static int grep_submodule(struct grep_opt *opt,
 	 * store is no longer global and instead is a member of the repository
 	 * object.
 	 */
-	add_to_alternates_memory(subrepo.objects->odb->path);
+	add_submodule_odb_by_path(subrepo.objects->odb->path);
 	obj_read_unlock();
 
 	memcpy(&subopt, opt, sizeof(subopt));
diff --git a/submodule.c b/submodule.c
index 8fde90e906..8de1aecaeb 100644
--- a/submodule.c
+++ b/submodule.c
@@ -187,6 +187,11 @@ int add_submodule_odb(const char *path)
 	return ret;
 }
 
+void add_submodule_odb_by_path(const char *path)
+{
+	string_list_insert(&added_submodule_odb_paths, xstrdup(path));
+}
+
 int register_all_submodule_odb_as_alternates(void)
 {
 	int i;
diff --git a/submodule.h b/submodule.h
index c252784bc2..17a06cc43b 100644
--- a/submodule.h
+++ b/submodule.h
@@ -104,6 +104,7 @@ int bad_to_remove_submodule(const char *path, unsigned flags);
  * the_repository.
  */
 int add_submodule_odb(const char *path);
+void add_submodule_odb_by_path(const char *path);
 int register_all_submodule_odb_as_alternates(void);
 
 /*