diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index 71d94f40..ac0abf7e 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -293,7 +293,7 @@ module ActiveModel
       #     { :name => :string, :age => :integer }
       #
       # The +associations+ hash looks like this:
-           { :posts => { :has_many => :posts } }
+      #     { :posts => { :has_many => :posts } }
       #
       # If :key is used:
       #