diff --git a/blender_cloud/attract/__init__.py b/blender_cloud/attract/__init__.py
index ea3a027..a6bd046 100644
--- a/blender_cloud/attract/__init__.py
+++ b/blender_cloud/attract/__init__.py
@@ -934,7 +934,7 @@ class ATTRACT_OT_project_open_in_browser(Operator):
             import pprint
             log.debug('found project: %s', pprint.pformat(project.to_dict()))
 
-        url = urllib.parse.urljoin(PILLAR_WEB_SERVER_URL, f'attract/{project.url}')
+        url = urllib.parse.urljoin(PILLAR_WEB_SERVER_URL, 'attract/' + project.url)
         webbrowser.open_new_tab(url)
         self.report({'INFO'}, 'Opened a browser at %s' % url)
 
diff --git a/blender_cloud/attract/draw.py b/blender_cloud/attract/draw.py
index 733dd4f..ebf3c59 100644
--- a/blender_cloud/attract/draw.py
+++ b/blender_cloud/attract/draw.py
@@ -179,8 +179,8 @@ def draw_callback_px(line_drawer: AttractLineDrawer):
 
     strips = shown_strips(context)
 
-    coords: typing.List[Float2] = []
-    colors: typing.List[Float4] = []
+    coords = []  # type: typing.List[Float2]
+    colors = []  # type: typing.List[Float4]
 
     # Collect all the lines (vertex coords + vertex colours) to draw.
     for strip in strips: