diff --git a/core/doc/helper.rst b/core/doc/helper.rst
index 052f140073a6e98047f51043f5eedb4e224be587..5de671aed8587d79f96b2995becd0d05f25de59f 100644
--- a/core/doc/helper.rst
+++ b/core/doc/helper.rst
@@ -46,16 +46,16 @@ File Tests
   :hide:
 
   import os
-  import argparse
   import tempfile
   from promod3.core import helper
+  from promod3.core import pm3argparse
 
   (fh, fn) = tempfile.mkstemp(suffix='.pdb')
   os.close(fh)
 
-  p = argparse.ArgumentParser()
+  p = pm3argparse.PM3ArgumentParser()
   p.add_argument('file', type=str)
-  opts = p.parse_args([fn])
+  opts = p.Parse([fn])
 
   helper.FileExists('Test file', 1, opts.file)
 
@@ -68,12 +68,12 @@ File Tests
 
 .. doctest:: helper
 
-  import argparse
   from promod3.core import helper
+  from promod3.core import pm3argparse
 
-  p = argparse.ArgumentParser()
+  p = pm3argparse.PM3ArgumentParser()
   p.add_argument('file', type=str)
-  opts = p.parse_args()
+  opts = p.Parse()
 
   helper.FileExists('Test file', 1, opts.file)