diff --git a/cime_config/acme/machines/config_machines.xml b/cime_config/acme/machines/config_machines.xml
index 9ead3bf4d887..bd79c243d960 100644
--- a/cime_config/acme/machines/config_machines.xml
+++ b/cime_config/acme/machines/config_machines.xml
@@ -963,6 +963,7 @@
          <DOUT_S_ROOT>/home/$USER/models/ACME/run/archive/$CASE</DOUT_S_ROOT>
 	 <BATCH_SYSTEM>pbs</BATCH_SYSTEM>
          <SUPPORTED_BY>dmricciuto</SUPPORTED_BY>
+         <OS>LINUX</OS>
          <GMAKE_J>32</GMAKE_J>
          <MAX_TASKS_PER_NODE>32</MAX_TASKS_PER_NODE>
          <mpirun mpilib="mpich">