diff --git a/libcutils/include/cutils/multiuser.h b/libcutils/include/cutils/multiuser.h
index 5bd9c7b..9a2305c 100644
--- a/libcutils/include/cutils/multiuser.h
+++ b/libcutils/include/cutils/multiuser.h
@@ -33,6 +33,7 @@
 
 extern gid_t multiuser_get_cache_gid(userid_t user_id, appid_t app_id);
 extern gid_t multiuser_get_ext_gid(userid_t user_id, appid_t app_id);
+extern gid_t multiuser_get_ext_cache_gid(userid_t user_id, appid_t app_id);
 extern gid_t multiuser_get_shared_gid(userid_t user_id, appid_t app_id);
 
 /* TODO: switch callers over to multiuser_get_shared_gid() */
diff --git a/libcutils/include/private/android_filesystem_config.h b/libcutils/include/private/android_filesystem_config.h
index 0037f15..bbba853 100644
--- a/libcutils/include/private/android_filesystem_config.h
+++ b/libcutils/include/private/android_filesystem_config.h
@@ -171,6 +171,9 @@
 #define AID_EXT_GID_START 30000 /* start of gids for apps to mark external data */
 #define AID_EXT_GID_END 39999   /* end of gids for apps to mark external data */
 
+#define AID_EXT_CACHE_GID_START 40000 /* start of gids for apps to mark external cached data */
+#define AID_EXT_CACHE_GID_END 49999   /* end of gids for apps to mark external cached data */
+
 #define AID_SHARED_GID_START 50000 /* start of gids for apps in each user to share */
 #define AID_SHARED_GID_END 59999   /* end of gids for apps in each user to share */
 
diff --git a/libcutils/multiuser.c b/libcutils/multiuser.c
index 08d4d6c..61403f4 100644
--- a/libcutils/multiuser.c
+++ b/libcutils/multiuser.c
@@ -45,6 +45,14 @@
     }
 }
 
+gid_t multiuser_get_ext_cache_gid(userid_t user_id, appid_t app_id) {
+    if (app_id >= AID_APP_START && app_id <= AID_APP_END) {
+        return multiuser_get_uid(user_id, (app_id - AID_APP_START) + AID_EXT_CACHE_GID_START);
+    } else {
+        return -1;
+    }
+}
+
 gid_t multiuser_get_shared_gid(userid_t user_id, appid_t app_id) {
     if (app_id >= AID_APP_START && app_id <= AID_APP_END) {
         return multiuser_get_uid(user_id, (app_id - AID_APP_START) + AID_SHARED_GID_START);
diff --git a/libcutils/tests/multiuser_test.cpp b/libcutils/tests/multiuser_test.cpp
index ae5c416..2f9d854 100644
--- a/libcutils/tests/multiuser_test.cpp
+++ b/libcutils/tests/multiuser_test.cpp
@@ -68,6 +68,14 @@
     EXPECT_EQ(1030000U, multiuser_get_ext_gid(10, 10000));
 }
 
+TEST(MultiuserTest, TestExtCache) {
+    EXPECT_EQ(ERR_GID, multiuser_get_ext_cache_gid(0, 0));
+    EXPECT_EQ(ERR_GID, multiuser_get_ext_cache_gid(0, 1000));
+    EXPECT_EQ(40000U, multiuser_get_ext_cache_gid(0, 10000));
+    EXPECT_EQ(ERR_GID, multiuser_get_ext_cache_gid(0, 50000));
+    EXPECT_EQ(1040000U, multiuser_get_ext_cache_gid(10, 10000));
+}
+
 TEST(MultiuserTest, TestShared) {
     EXPECT_EQ(ERR_GID, multiuser_get_shared_gid(0, 0));
     EXPECT_EQ(ERR_GID, multiuser_get_shared_gid(0, 1000));