diff --git a/nipype/interfaces/io.py b/nipype/interfaces/io.py
index ed5c0b5f9f..fad7b983d4 100644
--- a/nipype/interfaces/io.py
+++ b/nipype/interfaces/io.py
@@ -664,6 +664,9 @@ def _list_outputs(self):
                     outputs[key][i] = self.s3tolocal(path, bkt)
             elif type(outputs[key]) == str:
                 outputs[key] = self.s3tolocal(outputs[key], bkt)
+            else:
+                outputs[key] = self.s3tolocal(outputs[key], bkt)
+
 
         return outputs