diff --git a/mapper/benchmark_test.go b/mapper/benchmark_test.go
index 289cd8c..71cef1d 100644
--- a/mapper/benchmark_test.go
+++ b/mapper/benchmark_test.go
@@ -167,8 +167,7 @@
 
 	opts := MappingOptions{Direction: AtoB}
 
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for b.Loop() {
 		_, err := mapper.ApplyResponseMappings("bench-response", opts, responseData)
 		if err != nil {
 			b.Fatalf("ApplyResponseMappings failed: %v", err)
@@ -211,8 +210,7 @@
 
 	opts := MappingOptions{Direction: true}
 
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for b.Loop() {
 		_, err := mapper.ApplyQueryMappings("many-rules", opts, testData)
 		if err != nil {
 			b.Fatalf("ApplyQueryMappings failed: %v", err)
diff --git a/mapper/corpus.go b/mapper/corpus.go
index f3f2b0c..18759d6 100644
--- a/mapper/corpus.go
+++ b/mapper/corpus.go
@@ -653,10 +653,11 @@
 	switch n := node.(type) {
 	case *parser.CorpusField:
 		entry := map[string]any{
-			"@type":  "koral:field",
-			"key":    n.Key,
-			"value":  n.Value,
-			"mapped": true,
+			"@type":   "koral:field",
+			"key":     n.Key,
+			"value":   n.Value,
+			"mapped":  true,
+			"comment": "notinindex",
 		}
 		if n.Type != "" {
 			entry["type"] = "type:" + n.Type
diff --git a/mapper/corpus_test.go b/mapper/corpus_test.go
index 27a1a3c..02964fc 100644
--- a/mapper/corpus_test.go
+++ b/mapper/corpus_test.go
@@ -545,6 +545,7 @@
 	assert.Equal(t, "textClass", mapped["key"])
 	assert.Equal(t, "novel", mapped["value"])
 	assert.Equal(t, true, mapped["mapped"])
+	assert.Equal(t, "notinindex", mapped["comment"])
 }
 
 func TestCorpusResponseNoMatch(t *testing.T) {
@@ -593,11 +594,13 @@
 	assert.Equal(t, "genre", mapped1["key"])
 	assert.Equal(t, "science", mapped1["value"])
 	assert.Equal(t, true, mapped1["mapped"])
+	assert.Equal(t, "notinindex", mapped1["comment"])
 
 	mapped2 := fields[2].(map[string]any)
 	assert.Equal(t, "genre", mapped2["key"])
 	assert.Equal(t, "popsci", mapped2["value"])
 	assert.Equal(t, true, mapped2["mapped"])
+	assert.Equal(t, "notinindex", mapped2["comment"])
 }
 
 func TestCorpusResponseWikiDeReKoFixtureEnrichment(t *testing.T) {