diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index faab5c77..c4630ab6 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -199,12 +199,12 @@ module ActiveModel
       opts
     end
 
-    private
-
     def self.serializers_cache
-      @serializers_cache ||= Threadsafe::Cache.new
+      @serializers_cache ||= ThreadSafe::Cache.new
     end
 
+    private
+
     def self.get_serializer_for(klass)
       serializers_cache.fetch_or_store(klass) do
         serializer_class_name = "#{klass.name}Serializer"
diff --git a/lib/active_model_serializers.rb b/lib/active_model_serializers.rb
index f566280e..31925583 100644
--- a/lib/active_model_serializers.rb
+++ b/lib/active_model_serializers.rb
@@ -9,6 +9,9 @@ begin
 
   ActiveSupport.on_load(:action_controller) do
     include ::ActionController::Serialization
+    ActionDispatch::Reloader.to_prepare do
+      ActiveModel::Serializer.serializers_cache.clear
+    end
   end
 rescue LoadError
   # rails not installed, continuing