diff --git a/drivers/tee/optee/supplicant.c b/drivers/tee/optee/supplicant.c
index b1ea65b..c5726ec 100644
--- a/drivers/tee/optee/supplicant.c
+++ b/drivers/tee/optee/supplicant.c
@@ -82,8 +82,8 @@
 		cmd_shm_free(arg);
 		break;
 	case OPTEE_MSG_RPC_CMD_FS:
-		debug("OPTEE_MSG_RPC_CMD_FS not implemented\n");
-		arg->ret = TEE_ERROR_NOT_IMPLEMENTED;
+		debug("REE FS storage isn't available\n");
+		arg->ret = TEE_ERROR_STORAGE_NOT_AVAILABLE;
 		break;
 	case OPTEE_MSG_RPC_CMD_RPMB:
 		optee_suppl_cmd_rpmb(dev, arg);