diff --git a/tools/testing/selftests/ublk/kublk.h b/tools/testing/selftests/ublk/kublk.h
index 1b8833a40064..39839c711c79 100644
--- a/tools/testing/selftests/ublk/kublk.h
+++ b/tools/testing/selftests/ublk/kublk.h
@@ -220,7 +220,7 @@ static inline __u64 build_user_data(unsigned tag, unsigned op,
 		unsigned tgt_data, unsigned q_id, unsigned is_target_io)
 {
 	/* we only have 7 bits to encode q_id */
-	_Static_assert(UBLK_MAX_QUEUES_SHIFT <= 7);
+	_Static_assert(UBLK_MAX_QUEUES_SHIFT <= 7, "UBLK_MAX_QUEUES_SHIFT must be <= 7");
 	assert(!(tag >> 16) && !(op >> 8) && !(tgt_data >> 16) && !(q_id >> 7));
 
 	return tag | (op << 16) | (tgt_data << 24) |