diff --git a/program/js/app.js b/program/js/app.js
index a5c7db441..3bb6a0e50 100644
--- a/program/js/app.js
+++ b/program/js/app.js
@@ -1827,7 +1827,7 @@ function rcube_webmail()
         html = '<span id="flagicn'+uid+'" class="'+css_class+'">&nbsp;</span>';
       }
       else if (c == 'attachment') {
-        if (/application\/|multipart\/m/.test(flags.ctype))
+        if (/application\/|multipart\/(m|signed)/.test(flags.ctype))
           html = '<span class="attachment">&nbsp;</span>';
         else if (/multipart\/report/.test(flags.ctype))
           html = '<span class="report">&nbsp;</span>';