diff --git a/dev/buildbot/master/master.cfg b/dev/buildbot/master/master.cfg
index 45e721e5..01fdafba 100644
--- a/dev/buildbot/master/master.cfg
+++ b/dev/buildbot/master/master.cfg
@@ -461,7 +461,7 @@ def pythonFactory(pyID, pyCFG=PythonSlaveConfig("name")):
     # Create the factory to add the actions to
     factory = getBaseFactory()
     # Upgrade cython
-    factory.addStep(ShellCommand(command='pip install --upgrade cython', workdir=workingFolder, haltOnFailure=True))
+    factory.addStep(ShellCommand(command=combinedCMD('pip install --upgrade cython'), workdir=workingFolder, haltOnFailure=True))
     # 
     # Install dependencies
     if installPackages and False: # disabled