diff --git a/app/models/message.rb b/app/models/message.rb
index <HASH>..<HASH> 100644
--- a/app/models/message.rb
+++ b/app/models/message.rb
@@ -31,6 +31,7 @@ class Message
 
     @additionals = Hash.new
     plain.to_hash.keys.each do |key|
+      key = key.to_s
       value = plain[key]
       if key[0,1] == ADDITIONAL_FIELD_SEPARATOR and !RESERVED_ADDITIONAL_FIELDS.include?(key.to_s)
         @additionals[key[1, key.length]] = value
fix ruby <I> incompatibility in full message view #WEBINTERFACE-<I>