diff --git a/backend/pkg/uxtesting/uxtesting.go b/backend/pkg/uxtesting/uxtesting.go
index 2784f20b2..9893b1d87 100644
--- a/backend/pkg/uxtesting/uxtesting.go
+++ b/backend/pkg/uxtesting/uxtesting.go
@@ -123,7 +123,7 @@ func (u *uxTestingImpl) SetTaskSignal(signal *TaskSignal) error {
 		INSERT INTO ut_tests_signals (
 			session_id, test_id, task_id, status, comment, timestamp, duration
 		) VALUES (
-			$1, $2, $3, $4, $5, $6,
+			$1, $2, $3, $4, NULLIF($5, ''), $6,
 		    CASE
         		WHEN $7 <= 0 THEN NULL
         		ELSE $7