diff --git a/pkg/base-dev/mar/noun.hoon b/pkg/base-dev/mar/noun.hoon
index f5aba873e0..ff5443ec46 100644
--- a/pkg/base-dev/mar/noun.hoon
+++ b/pkg/base-dev/mar/noun.hoon
@@ -9,7 +9,7 @@
           ++  noun  *
           --
 ++  grow  |%
-          ++  mime  [/application/octet-stream (as-octs:mimes:html (jam non))]
+          ++  mime  [/application/x-urb-jam (as-octs:mimes:html (jam non))]
           --
 ++  grad
   |%