diff --git a/pkg/index/index.go b/pkg/index/index.go
index 9491bf4..b6eec5c 100644
--- a/pkg/index/index.go
+++ b/pkg/index/index.go
@@ -15,8 +15,10 @@ import (
 
 const (
 	maxSearchResult = 101
-
-	docType = "page"
+	docType         = "page"
+	titleField      = "title"
+	storeTitleField = "store_title"
+	searchField     = "search"
 )
 
 type indexPage struct {
@@ -110,7 +112,7 @@ func (i *Index) Search(search string) (results []core.Result, err error) {
 			continue
 		}
 		for fragField, frags := range hit.Fragments {
-			if fragField == "title" || fragField == "search" {
+			if fragField == titleField || fragField == searchField {
 				for _, f := range frags {
 					r.HTML += template.HTML(f)
 				}
diff --git a/pkg/index/mapping.go b/pkg/index/mapping.go
index aa13d60..25c9337 100644
--- a/pkg/index/mapping.go
+++ b/pkg/index/mapping.go
@@ -11,10 +11,15 @@ import (
 	"github.com/blevesearch/bleve/mapping"
 )
 
+const (
+	bigram = "bigram_tokenfilter"
+	ngram  = "fulltext_ngram"
+)
+
 func createMapping() (m *mapping.IndexMappingImpl, err error) {
 	m = bleve.NewIndexMapping()
 
-	err = m.AddCustomTokenFilter("bigram_tokenfilter", map[string]interface{}{
+	err = m.AddCustomTokenFilter(bigram, map[string]interface{}{
 		"type": edgengram.Name,
 		"side": edgengram.FRONT,
 		"min":  3.0,
@@ -23,12 +28,12 @@ func createMapping() (m *mapping.IndexMappingImpl, err error) {
 	if err != nil {
 		return
 	}
-	err = m.AddCustomAnalyzer("fulltext_ngram", map[string]interface{}{
+	err = m.AddCustomAnalyzer(ngram, map[string]interface{}{
 		"type":      custom.Name,
 		"tokenizer": unicode.Name,
 		"token_filters": []string{
 			lowercase.Name,
-			"bigram_tokenfilter",
+			bigram,
 		},
 	})
 	if err != nil {
@@ -37,14 +42,14 @@ func createMapping() (m *mapping.IndexMappingImpl, err error) {
 
 	doc := bleve.NewDocumentMapping()
 	ti := bleve.NewTextFieldMapping()
-	ti.Analyzer = "fulltext_ngram"
-	doc.AddFieldMappingsAt("title", ti)
+	ti.Analyzer = ngram
+	doc.AddFieldMappingsAt(titleField, ti)
 	st := bleve.NewTextFieldMapping()
-	st.Analyzer = "fulltext_ngram"
-	doc.AddFieldMappingsAt("store_title", st)
+	st.Analyzer = ngram
+	doc.AddFieldMappingsAt(storeTitleField, st)
 	s := bleve.NewTextFieldMapping()
-	s.Analyzer = "fulltext_ngram"
-	doc.AddFieldMappingsAt("search", s)
+	s.Analyzer = ngram
+	doc.AddFieldMappingsAt(searchField, s)
 
 	m.AddDocumentMapping(docType, doc)
 	return