diff --git a/fsl/utils/fslsub.py b/fsl/utils/fslsub.py
index 98727382338fa2c6271ff975970a3f952dfafc47..f23630d4447d989dc588313a0d3c36eff79e7dbf 100644
--- a/fsl/utils/fslsub.py
+++ b/fsl/utils/fslsub.py
@@ -375,7 +375,7 @@ else:
 
 res = func(*args, **kwargs)
 if res is not None:
-    with open(__file__ + '_out.pickle') as f:
+    with open(__file__ + '_out.pickle', 'w') as f:
         pickle.dump(f, res)
 """