diff --git a/docs/content/doc/advanced/config-cheat-sheet.en-us.md b/docs/content/doc/advanced/config-cheat-sheet.en-us.md
index affb90eef7..c12c05c43e 100644
--- a/docs/content/doc/advanced/config-cheat-sheet.en-us.md
+++ b/docs/content/doc/advanced/config-cheat-sheet.en-us.md
@@ -177,8 +177,8 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
 
 - `REPO_INDEXER_ENABLED`: **false**: Enables code search (uses a lot of disk space, about 6 times more than the repository size).
 - `REPO_INDEXER_PATH`: **indexers/repos.bleve**: Index file used for code search.
-- `REPO_INDEXER_EXTENSIONS`: **empty**: A comma separated list of file extensions to include/exclude from the index; a \`.' matches files with no extension. An empty list means include all files, disregarding `REPO_EXTENSIONS_LIST_EXCLUDE`.
-- `REPO_EXTENSIONS_LIST_EXCLUDE`: **false**: If true, `REPO_INDEXER_EXTENSIONS` are the file extensions to exclude rather than include in the index.
+- `REPO_INDEXER_EXTENSIONS`: **empty**: A comma separated list of file extensions to exclude from the index; a \`.' matches files with no extension. An empty list means do not exclude any files.
+- `REPO_EXTENSIONS_LIST_INCLUDE`: **false**: If true, `REPO_INDEXER_EXTENSIONS` are the file extensions to include rather than exclude from the index.
 - `UPDATE_BUFFER_LEN`: **20**: Buffer length of index request.
 - `MAX_FILE_SIZE`: **1048576**: Maximum size in bytes of files to be indexed.
 
diff --git a/models/repo_indexer.go b/models/repo_indexer.go
index d54b9e397e..dd36cf9312 100644
--- a/models/repo_indexer.go
+++ b/models/repo_indexer.go
@@ -239,7 +239,7 @@ func isIndexable(entry *git.TreeEntry) bool {
 		if cnt > 1 {
 			ext = strings.ToLower(parts[cnt-1])
 		}
-		if setting.Indexer.FileExtensions[ext] == setting.Indexer.ExcludeExtensions {
+		if setting.Indexer.FileExtensions[ext] != setting.Indexer.IncludeExtensions {
 			return false
 		}
 	}
diff --git a/modules/setting/indexer.go b/modules/setting/indexer.go
index ef3a45eabb..304eada607 100644
--- a/modules/setting/indexer.go
+++ b/modules/setting/indexer.go
@@ -31,7 +31,7 @@ var (
 		IssueQueueConnStr     string
 		IssueQueueBatchNumber int
 		FileExtensions        map[string]bool
-		ExcludeExtensions     bool
+		IncludeExtensions     bool
 	}{
 		IssueType:             "bleve",
 		IssuePath:             "indexers/issues.bleve",
@@ -55,7 +55,7 @@ func newIndexerService() {
 		Indexer.RepoPath = path.Join(AppWorkPath, Indexer.RepoPath)
 	}
 	Indexer.FileExtensions = extensionsFromString(sec.Key("REPO_INDEXER_EXTENSIONS").MustString(""))
-	Indexer.ExcludeExtensions = sec.Key("REPO_EXTENSIONS_LIST_EXCLUDE").MustBool(false)
+	Indexer.IncludeExtensions = sec.Key("REPO_EXTENSIONS_LIST_INCLUDE").MustBool(false)
 
 	Indexer.UpdateQueueLength = sec.Key("UPDATE_BUFFER_LEN").MustInt(20)
 	Indexer.MaxIndexerFileSize = sec.Key("MAX_FILE_SIZE").MustInt64(1024 * 1024)
@@ -69,10 +69,19 @@ func extensionsFromString(from string) map[string]bool {
 	extmap := make(map[string]bool)
 	for _, ext := range strings.Split(strings.ToLower(from), ",") {
 		ext = strings.TrimSpace(ext)
+		// Accept *.txt, .txt and txt. Also use . to mean no ext
+		if strings.HasPrefix(ext, "*.") {
+			ext = ext[1:]
+		}
 		if ext == "." {
 			extmap[""] = true
-		} else if ext != "" && !strings.Contains(ext, ".") {
-			extmap[ext] = true
+		} else {
+			if strings.HasPrefix(ext, ".") {
+				ext = ext[1:]
+			}
+			if ext != "" {
+				extmap[ext] = true
+			}
 		}
 	}
 	if len(extmap) == 0 {