diff --git a/web/viewer.html b/web/viewer.html
index 787c65dfa..762de689c 100644
--- a/web/viewer.html
+++ b/web/viewer.html
@@ -44,10 +44,6 @@ See https://github.com/adobe-type-tools/cmap-resources
     <link rel="resource" type="application/l10n" href="locale/locale.properties">
 <!--#endif-->
 
-<!--#if !PRODUCTION-->
-    <script src="../src/shared/compatibility.js"></script>
-<!--#endif-->
-
 <!--#if !PRODUCTION-->
     <script src="../node_modules/systemjs/dist/system.js"></script>
     <script src="../systemjs.config.js"></script>