diff --git a/lib/wonkavision/message_mapper/map.rb b/lib/wonkavision/message_mapper/map.rb
index <HASH>..<HASH> 100644
--- a/lib/wonkavision/message_mapper/map.rb
+++ b/lib/wonkavision/message_mapper/map.rb
@@ -20,6 +20,7 @@ module Wonkavision
 
       def from (context,&block)
         raise "No block ws provided to 'from'" unless block
+        context = HashWithIndifferentAccess.new if context.nil?
         @context_stack.push(context)
         instance_eval(&block)
         @context_stack.pop
Substitute empty hash for context when "from" is called with 'nil' in a MessageMapper map