diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 22cc6cac0ba2..7eb94894bd68 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -201,7 +201,7 @@ struct tcmu_tmr {
 
 	uint8_t tmr_type;
 	uint32_t tmr_cmd_cnt;
-	int16_t tmr_cmd_ids[];
+	int16_t tmr_cmd_ids[] __counted_by(tmr_cmd_cnt);
 };
 
 /*