diff --git a/dev/buildbot/master/master.cfg b/dev/buildbot/master/master.cfg
index 59a9424e..a8ad2e5e 100644
--- a/dev/buildbot/master/master.cfg
+++ b/dev/buildbot/master/master.cfg
@@ -1085,7 +1085,7 @@ for platform in ['OSX', 'linux', 'windows']:
                           slavenames=[platform + platmod +"-slave"],
                           factory = cmake_slave(wrapper,
                                                 platform = platform,
-                                                cmake_env = cmake_env
+                                                cmake_env = cmake_env,
                                                 ctest_args = ctest_args,
                                                 cmake_args = cmake_args,
                                                 build_args = build_args)