diff --git a/modules/highlight/highlight.go b/modules/highlight/highlight.go
index c3b504dfb..fc9a4ad10 100644
--- a/modules/highlight/highlight.go
+++ b/modules/highlight/highlight.go
@@ -63,7 +63,9 @@ var (
 	}
 
 	// Extensions that are not same as highlight classes.
-	highlightMapping = map[string]string{}
+	highlightMapping = map[string]string{
+		".txt": "nohighlight",
+	}
 )
 
 // NewContext loads highlight map