diff --git a/lib/logstorage/pipe_sort_test.go b/lib/logstorage/pipe_sort_test.go
index dab5c12f7..10b6564fb 100644
--- a/lib/logstorage/pipe_sort_test.go
+++ b/lib/logstorage/pipe_sort_test.go
@@ -152,6 +152,7 @@ func TestPipeSort(t *testing.T) {
 		{
 			{"_msg", `def`},
 			{"a", `1`},
+			{"b", ""},
 		},
 	})
 
@@ -246,6 +247,7 @@ func TestPipeSort(t *testing.T) {
 		{
 			{"_msg", `def`},
 			{"a", `1`},
+			{"b", ""},
 		},
 	})
 }