diff --git a/nipype/pipeline/plugins/base.py b/nipype/pipeline/plugins/base.py
index f37bcff883..9ef1ec3e43 100644
--- a/nipype/pipeline/plugins/base.py
+++ b/nipype/pipeline/plugins/base.py
@@ -528,15 +528,15 @@ def run(self, graph, config, updatehash=False):
         pyfiles = []
         dependencies = {}
         self._config = config
-        nodes = nx.topological_sort(graph)
+        nodes = list(nx.topological_sort(graph))
         logger.debug('Creating executable python files for each node')
         for idx, node in enumerate(nodes):
             pyfiles.append(
                 create_pyscript(
                     node, updatehash=updatehash, store_exception=False))
             dependencies[idx] = [
-                nodes.index(prevnode) for prevnode in graph.predecessors(node)
-            ]
+                nodes.index(prevnode)
+                for prevnode in list(graph.predecessors(node))]
         self._submit_graph(pyfiles, dependencies, nodes)
 
     def _get_args(self, node, keywords):