diff --git a/lib/waffle/definition/versioning.ex b/lib/waffle/definition/versioning.ex
index 06ee5e6..8905b6b 100644
--- a/lib/waffle/definition/versioning.ex
+++ b/lib/waffle/definition/versioning.ex
@@ -28,6 +28,9 @@ defmodule Waffle.Definition.Versioning do
     quote do
       @versions [:original]
       @before_compile Waffle.Definition.Versioning
+
+      def extension(_, {file, _}), do: Path.extname(file.file_name)
+      defoverridable extension: 2
     end
   end
 
@@ -38,7 +41,7 @@ defmodule Waffle.Definition.Versioning do
     case conversion do
       :skip       -> nil
       {_, _, ext} -> "#{name}.#{ext}"
-       _          -> "#{name}#{Path.extname(file.file_name)}"
+       _          -> "#{name}#{definition.extension(version, {file, scope})}"
     end
   end
 
diff --git a/test/actions/store_test.exs b/test/actions/store_test.exs
index 439c8ab..d2574e7 100644
--- a/test/actions/store_test.exs
+++ b/test/actions/store_test.exs
@@ -16,6 +16,7 @@ defmodule WaffleTest.Actions.Store do
     def transform(:skipped, _), do: :skip
     def transform(_, _), do: :noaction
     def __versions, do: [:original, :thumb, :skipped]
+    def extension(_, {file, _}), do: Path.extname(file.file_name)
   end
 
   defmodule DummyDefinitionWithHeaders do
@@ -24,6 +25,7 @@ defmodule WaffleTest.Actions.Store do
 
     def transform(_, _), do: :noaction
     def __versions, do: [:original, :thumb, :skipped]
+    def extension(_, {file, _}), do: Path.extname(file.file_name)
     def remote_file_headers(%URI{host: "www.google.com"}), do: [{"User-Agent", "MyApp"}]
   end
 
@@ -36,6 +38,16 @@ defmodule WaffleTest.Actions.Store do
     def __versions, do: [:original, :thumb, :skipped]
   end
 
+  defmodule DummyDefinitionWithExtension do
+    use Waffle.Actions.Store
+    use Waffle.Definition.Storage
+
+    def validate({file, _}), do: true
+    def transform(_, _), do: :noaction
+    def __versions, do: [:original]
+    def extension(_, {file, _}), do: ".jpeg"
+  end
+
   test "checks file existence" do
     assert DummyDefinition.store("non-existent-file.png") == {:error, :invalid_file_path}
   end
@@ -151,6 +163,15 @@ defmodule WaffleTest.Actions.Store do
     end
   end
 
+  test "sets extension from extension/2" do
+    with_mock Waffle.Storage.S3,
+      put: fn DummyDefinitionWithExtension, _, {%{file_name: "image.jpeg", path: @img}, nil} ->
+        {:ok, "resp"}
+      end do
+      assert DummyDefinitionWithExtension.store(@img) == {:ok, "image.png"}
+    end
+  end
+
   test "sets remote filename from content-disposition header when available" do
     with_mocks([
       {
diff --git a/test/actions/url_test.exs b/test/actions/url_test.exs
index cc88127..2bb0611 100644
--- a/test/actions/url_test.exs
+++ b/test/actions/url_test.exs
@@ -9,6 +9,7 @@ defmodule WaffleTest.Actions.Url do
     def __versions, do: [:original, :thumb, :skipped]
     def transform(:skipped, _), do: :skip
     def transform(_, _), do: :noaction
+    def extension(_, {file, _}), do: Path.extname(file.file_name)
     def default_url(version, scope) when is_nil(scope), do: "dummy-#{version}"
     def default_url(version, scope), do: "dummy-#{version}-#{scope}"
     def __storage, do: Waffle.Storage.S3