Does not replace links with no number

app/helpers/digest_helper.rb

@@ -3,6 +3,6 @@ module DigestHelper
   # Important mechanism, to ensure the digest will not have the same footnote
   # link multiple times
   def renumber_footnotes(id, description)
-    description.gsub(/\[(\d)*\]/, "[#{id}_\\1]")
+    description.gsub(/\[(\d)+\]/, "[#{id}_\\1]")
   end
 end