diff --git a/ush/run_batch.py b/ush/run_batch.py
index 111e9c3..e4ddaa1 100644
--- a/ush/run_batch.py
+++ b/ush/run_batch.py
@@ -105,6 +105,7 @@
             job_card.write('#PBS -l place=vscatter,select=1'
                            +':ncpus='+nproc+':mem=4GB'+'\n')
         job_card.write('\n')
+        job_card.write('export OMP_NUM_THREADS=1\n')
         job_card.write('cd $PBS_O_WORKDIR\n')
     job_card.write('\n')
     job_card.write('/bin/sh '+script)