diff --git a/setup.cfg b/setup.cfg
index 0c3407922..ad81baa62 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -18,3 +18,4 @@ frameworks = CoreFoundation, Foundation, AppKit
 known_standard_library=unicodedata
 line_length=120
 skip=gtkui.py
+known_third_party=pygtk, gtk, gobject, gtk.gdk, pango, cairo, pangocairo