diff --git a/libs/gtkmm2ext/wscript b/libs/gtkmm2ext/wscript
index 59d9c35243..1afaca455e 100644
--- a/libs/gtkmm2ext/wscript
+++ b/libs/gtkmm2ext/wscript
@@ -66,7 +66,7 @@ gtkmm2ext_sources = [
         'treeutils.cc',
         'utils.cc',
         'visibility_tracker.cc',
-        'window_proxy.cc'
+        'window_proxy.cc',
         'window_title.cc'
 ]