diff --git a/lib/merb-core/controller/mixins/render.rb b/lib/merb-core/controller/mixins/render.rb
index 3253aba..c4e5fcc 100644
--- a/lib/merb-core/controller/mixins/render.rb
+++ b/lib/merb-core/controller/mixins/render.rb
@@ -445,7 +445,8 @@ module Merb::RenderMixin
     unless string || block_given?
       raise ArgumentError, "You must pass a block or a string into throw_content"
     end
-    @_caught_content[obj] = string.to_s << (block_given? ? capture(&block) : "")
+    @_caught_content[obj] ||= ''
+    @_caught_content[obj] << string.to_s << (block_given? ? capture(&block) : "")
   end
 
 end