diff --git a/nipype/pipeline/plugins/slurmgraph.py b/nipype/pipeline/plugins/slurmgraph.py
index 5e46c2b5cf..bb9af44066 100644
--- a/nipype/pipeline/plugins/slurmgraph.py
+++ b/nipype/pipeline/plugins/slurmgraph.py
@@ -53,6 +53,8 @@ def __init__(self, **kwargs):
                     self._template = open(self._template).read()
             if 'sbatch_args' in kwargs['plugin_args']:
                 self._sbatch_args = kwargs['plugin_args']['sbatch_args']
+            else:  # default argument for _sbatch_args
+                self._sbatch_args = ''
             if 'dont_resubmit_completed_jobs' in kwargs['plugin_args']:
                 self._dont_resubmit_completed_jobs = kwargs['plugin_args']['dont_resubmit_completed_jobs']
             else: