diff --git a/master.cfg b/master.cfg
index 9f2e660..828311c 100644
--- a/master.cfg
+++ b/master.cfg
@@ -238,7 +238,7 @@ def generic_builder(id, branch='', rsync=False):
                              maxsize=500 * 1024 * 1024,
                              workdir='install'))
     f.addStep(MasterShellCommand(name='unpack',
-                                 command=['python3.6',
+                                 command=['python3.7',
                                           unpack_script,
                                           filename],
                                  description='unpacking',