diff --git a/modules/htmlout/lib/htmlout.js b/modules/htmlout/lib/htmlout.js
index 29a0712b1..31b4bc647 100644
--- a/modules/htmlout/lib/htmlout.js
+++ b/modules/htmlout/lib/htmlout.js
@@ -198,6 +198,7 @@ var asExtsPlainText = [
     "bas",
     "hex",
     "inc",
+    "lst",
     "mac",
     "map",
     "nasm",