diff --git a/engine/reqfilter_test.go b/engine/reqfilter_test.go
index cb0eca74e..521e4a86c 100644
--- a/engine/reqfilter_test.go
+++ b/engine/reqfilter_test.go
@@ -78,8 +78,10 @@ func TestPassStringPrefix(t *testing.T) {
 		t.Error("Not passes filter")
 	}
 	rf = &RequestFilter{Type: MetaStringPrefix, FieldName: "nonexisting", Values: []string{"off"}}
-	if _, err := rf.passStringPrefix(cd, "ExtraFields"); err == nil || err != utils.ErrNotFound {
+	if passing, err := rf.passStringPrefix(cd, "ExtraFields"); err != nil {
 		t.Error(err)
+	} else if passing {
+		t.Error("Passes filter")
 	}
 }