diff --git a/app/models/dmsf_file_revision.rb b/app/models/dmsf_file_revision.rb
index d1910db6..e8799acd 100644
--- a/app/models/dmsf_file_revision.rb
+++ b/app/models/dmsf_file_revision.rb
@@ -270,7 +270,8 @@ class DmsfFileRevision < ActiveRecord::Base
     format2.sub!('%v', self.version)
     format2.sub!('%i', self.dmsf_file.id.to_s)
     format2.sub!('%r', self.id.to_s)
-    format2 + ext
+    format2 + ext if ext
+    format2
   end
 
   def self.create_digest(path)