diff --git a/master/custom/workers.py b/master/custom/workers.py
index fe089024..5eb9d265 100644
--- a/master/custom/workers.py
+++ b/master/custom/workers.py
@@ -321,6 +321,7 @@ def get_workers(settings):
         cpw(
             name="skumaran-ubuntu-x86_64",
             tags=['linux', 'unix', 'ubuntu', 'amd64', 'x86-64'],
+            parallel_tests=1,
         ),
         cpw(
             name="ware-alpine",