diff --git a/CHANGES.txt b/CHANGES.txt
index 049e4a6..a3bff28 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -5,6 +5,13 @@ unreleased
   the ``preprocessor`` will be wrapped in a function that invokes the 
   preprocessor with pyramid's config settings as the second argument.
 
+- `add_mako_renderer` now accepts a list of `extensions` instead of a single 
+  `extension`. This allows for multiple extensions to share a single lookup.
+  Under the previous system, `.mako` and `.mak` would be registered to different
+  render factories and template lookups; if a `.mako` referenced a `.mak` file,
+  then it would be compiled into the `.mako` template lookup and recompiled 
+  again for the `.mak` template lookup if accessed directly. 
+
 1.0.2 (2014-04-22)
 ==================
 
diff --git a/pyramid_mako/__init__.py b/pyramid_mako/__init__.py
index 1038306..59beb65 100644
--- a/pyramid_mako/__init__.py
+++ b/pyramid_mako/__init__.py
@@ -161,6 +161,7 @@ def __call__(self, value, system):
 
 class MakoRendererFactory(object):
     lookup = None
+    registered_extensions = None  # debugging only
     renderer_factory = staticmethod(MakoLookupTemplateRenderer) # testing
 
     def __call__(self, info):
@@ -238,8 +239,8 @@ def preprocessor_injector(template):
         preprocessor=preprocessor,
     )
 
-def add_mako_renderer(config, extension, settings_prefix='mako.'):
-    """ Register a Mako renderer for a template extension.
+def add_mako_renderer(config, extensions, settings_prefix='mako.'):
+    """ Register a Mako renderer for a template extension(s).
 
     This function is available on the Pyramid configurator after
     including the package:
@@ -250,19 +251,29 @@ def add_mako_renderer(config, extension, settings_prefix='mako.'):
 
     The renderer will load its configuration from a prefix in the Pyramid
     settings dictionary. The default prefix is 'mako.'.
+    
+    Multiple extensions can be registered to a single factory and template 
+    lookup by passing in a list or tuple for the extensions arg.
+
+    .. code-block:: python
+
+       config.add_mako_renderer(('.mako', '.mak'), settings_prefix='mako.')
     """
+    extensions = extensions if isinstance(extensions, (list, tuple)) else (extensions, )
     renderer_factory = MakoRendererFactory()
-    config.add_renderer(extension, renderer_factory)
+    renderer_factory.registered_extensions = extensions
+    for ext in extensions:
+        config.add_renderer(ext, renderer_factory)
 
     def register():
-        registry = config.registry
-        opts = parse_options_from_settings(
-            registry.settings, settings_prefix, config.maybe_dotted)
-        lookup = PkgResourceTemplateLookup(**opts)
+        if renderer_factory.lookup is None:
+            opts = parse_options_from_settings(
+                config.registry.settings, settings_prefix, config.maybe_dotted)
+            lookup = PkgResourceTemplateLookup(**opts)
+            renderer_factory.lookup = lookup
 
-        renderer_factory.lookup = lookup
-
-    config.action(('mako-renderer', extension), register)
+    for ext in extensions:
+        config.action(('mako-renderer', ext), register)
 
 def includeme(config):
     """ Set up standard configurator registrations.  Use via:
@@ -278,6 +289,6 @@ def includeme(config):
     :func:`~pyramid_mako.add_mako_renderer` documentation for more information.
     """
     config.add_directive('add_mako_renderer', add_mako_renderer)
-
-    config.add_mako_renderer('.mako')
-    config.add_mako_renderer('.mak')
+    config.add_mako_renderer(('.mako',
+                              '.mak', 
+                              ))
diff --git a/pyramid_mako/tests.py b/pyramid_mako/tests.py
index 59fee57..777c87b 100644
--- a/pyramid_mako/tests.py
+++ b/pyramid_mako/tests.py
@@ -641,6 +641,7 @@ def test_repr_and_str(self):
         self.assertEqual(str(exc), 'text')
         self.assertEqual(repr(exc), 'text')
 
+
 class DummyLookup(object):
     directories = True