diff --git a/lib/active_model/serializer/associations.rb b/lib/active_model/serializer/associations.rb
index 711eac4f..54967401 100644
--- a/lib/active_model/serializer/associations.rb
+++ b/lib/active_model/serializer/associations.rb
@@ -12,10 +12,6 @@ module ActiveModel
           options[:name] || @name
         end
 
-        def key
-          options[:key] || @name
-        end
-
         def root
           options[:root] || @name
         end