diff --git a/templates/widgets/zipFileField.hamlet b/templates/widgets/zipFileField.hamlet
index 1e39effa6..301d16c4b 100644
--- a/templates/widgets/zipFileField.hamlet
+++ b/templates/widgets/zipFileField.hamlet
@@ -4,5 +4,5 @@ $maybe exts <- fmap toNullable permittedExtensions
   <br>
   _{MsgUploadModeExtensionRestriction}: 
   <ul .list--inline .list--comma-separated .list--iconless>
-    $forall ext <- zipExtensions <> exts
+    $forall ext <- bool id (mappend zipExtensions) doUnpack exts
       <li style="font-family: monospace">#{ext}