diff --git a/actionmailer/lib/action_mailer.rb b/actionmailer/lib/action_mailer.rb
index 996740408b..891fe11101 100644
--- a/actionmailer/lib/action_mailer.rb
+++ b/actionmailer/lib/action_mailer.rb
@@ -73,6 +73,6 @@ def self.eager_load!
 
 ActiveSupport.on_load(:action_view) do
   ActionView::Base.default_formats ||= Mime::SET.symbols
-  ActionView::Template::Types.delegate_to Mime
+  ActionView::Template.mime_types_implementation = Mime
   ActionView::LookupContext::DetailsKey.clear
 end
diff --git a/actionpack/lib/action_dispatch.rb b/actionpack/lib/action_dispatch.rb
index 712e9a4014..37b2b54edc 100644
--- a/actionpack/lib/action_dispatch.rb
+++ b/actionpack/lib/action_dispatch.rb
@@ -147,6 +147,6 @@ def eager_load!
 
 ActiveSupport.on_load(:action_view) do
   ActionView::Base.default_formats ||= Mime::SET.symbols
-  ActionView::Template::Types.delegate_to Mime
+  ActionView::Template.mime_types_implementation = Mime
   ActionView::LookupContext::DetailsKey.clear
 end
diff --git a/actionpack/lib/action_dispatch/http/mime_type.rb b/actionpack/lib/action_dispatch/http/mime_type.rb
index 8553655d73..1bcf3007a2 100644
--- a/actionpack/lib/action_dispatch/http/mime_type.rb
+++ b/actionpack/lib/action_dispatch/http/mime_type.rb
@@ -42,6 +42,10 @@ def [](type)
       Type.lookup_by_extension(type)
     end
 
+    def symbols
+      SET.symbols
+    end
+
     def fetch(type, &block)
       return type if type.is_a?(Type)
       EXTENSION_LOOKUP.fetch(type.to_s, &block)
diff --git a/actionview/lib/action_view/template.rb b/actionview/lib/action_view/template.rb
index 607cdb71f2..50f2b547cf 100644
--- a/actionview/lib/action_view/template.rb
+++ b/actionview/lib/action_view/template.rb
@@ -109,6 +109,7 @@ class Template
       autoload :Handlers
       autoload :HTML
       autoload :Inline
+      autoload :Types
       autoload :Sources
       autoload :Text
       autoload :Types
@@ -119,6 +120,17 @@ class Template
     singleton_class.attr_accessor :frozen_string_literal
     @frozen_string_literal = false
 
+    class << self # :nodoc:
+      def mime_types_implementation=(implementation)
+        # This method isn't thread-safe, but it's not supposed
+        # to be called after initialization
+        if self::Types != implementation
+          remove_const(:Types)
+          const_set(:Types, implementation)
+        end
+      end
+    end
+
     attr_reader :identifier, :handler
     attr_reader :variable, :format, :variant, :virtual_path
 
diff --git a/actionview/lib/action_view/template/types.rb b/actionview/lib/action_view/template/types.rb
index dfb6c0999f..07bda733ce 100644
--- a/actionview/lib/action_view/template/types.rb
+++ b/actionview/lib/action_view/template/types.rb
@@ -4,53 +4,38 @@
 
 module ActionView
   class Template # :nodoc:
-    module Types
-      class Type
-        SET = Struct.new(:symbols).new([ :html, :text, :js, :css, :xml, :json ])
+    class SimpleType # :nodoc:
+      SET = Struct.new(:symbols).new([ :html, :text, :js, :css, :xml, :json ])
 
-        def self.[](type)
-          if type.is_a?(self)
-            type
-          else
-            new(type)
-          end
-        end
-
-        attr_reader :symbol
-
-        def initialize(symbol)
-          @symbol = symbol.to_sym
-        end
-
-        def to_s
-          @symbol.to_s
-        end
-        alias to_str to_s
-
-        def ref
-          @symbol
-        end
-        alias to_sym ref
-
-        def ==(type)
-          @symbol == type.to_sym unless type.blank?
+      def self.[](type)
+        if type.is_a?(self)
+          type
+        else
+          new(type)
         end
       end
 
-      class << self
-        attr_reader :symbols
+      attr_reader :symbol
 
-        def delegate_to(klass)
-          @symbols = klass::SET.symbols
-          @type_klass = klass
-        end
-
-        def [](type)
-          @type_klass[type]
-        end
+      def initialize(symbol)
+        @symbol = symbol.to_sym
       end
 
-      delegate_to Type
+      def to_s
+        @symbol.to_s
+      end
+      alias to_str to_s
+
+      def ref
+        @symbol
+      end
+      alias to_sym ref
+
+      def ==(type)
+        @symbol == type.to_sym unless type.blank?
+      end
     end
+
+    Types = SimpleType # :nodoc:
   end
 end
diff --git a/actionview/test/template/asset_tag_helper_test.rb b/actionview/test/template/asset_tag_helper_test.rb
index 11fe27869f..ae61e42fec 100644
--- a/actionview/test/template/asset_tag_helper_test.rb
+++ b/actionview/test/template/asset_tag_helper_test.rb
@@ -4,7 +4,7 @@
 require "active_support/ordered_options"
 
 require "action_dispatch"
-ActionView::Template::Types.delegate_to Mime
+ActionView::Template.mime_types_implementation = Mime
 
 module AssetTagHelperTestHelpers
   def with_preload_links_header(new_preload_links_header = true)