diff --git a/src/pyquickhelper/ipythonhelper/magic_parser.py b/src/pyquickhelper/ipythonhelper/magic_parser.py
index d23d15dbf..de318ab23 100644
--- a/src/pyquickhelper/ipythonhelper/magic_parser.py
+++ b/src/pyquickhelper/ipythonhelper/magic_parser.py
@@ -18,6 +18,48 @@ class MagicCommandParser (argparse.ArgumentParser):
     .. versionadded:: 0.9
     """
 
+    def __init__(self, *l, **p):
+        """
+        custom constructor, see `ArgumentParser <https://docs.python.org/3.4/library/argparse.html>`_
+        """
+        argparse.ArgumentParser.__init__(self, *l, **p)
+        self._keep_args = {}
+
+    @staticmethod
+    def _private_get_name(*args):
+        """
+        guesses the name of a parameter knowning the argument
+        given to @see me add_argument
+        """
+        for i, a in enumerate(args):
+            if isinstance(a, str):
+                if a[0] != "-":
+                    return a
+                elif a.startswith("--"):
+                    return a[2:].replace("-", "_")
+        raise KeyError("unable to find parameter name in: " + str(args))
+
+    def add_argument(self, *args, **kwargs):
+        """
+        overloads the methods, see `ArgumentParser <https://docs.python.org/3.4/library/argparse.html>`_
+        """
+        super(argparse.ArgumentParser, self).add_argument(*args, **kwargs)
+        if args != ('-h', '--help'):
+            name = MagicCommandParser._private_get_name(*args)
+            self._keep_args[name] = (args, kwargs)
+
+    def has_choices(self, name):
+        """
+        tells if a parameter has choises
+
+        @param      name        parameter name
+        @return                 boolean
+        """
+        if name not in self._keep_args:
+            raise KeyError("unable to find parameter name: {0} in {1}".format(
+                name, list(self._keep_args.keys())))
+        return "choices" in self._keep_args[name][1]
+
     def parse_cmd(self, line, context=None, fLOG=noLOG):
         """
         split line using `shlex <https://docs.python.org/3.4/library/shlex.html>`_
@@ -34,9 +76,13 @@ def parse_cmd(self, line, context=None, fLOG=noLOG):
         if context is not None:
             up = {}
             for k, v in res.__dict__.items():
-                ev = self.eval(v, context=context, fLOG=fLOG)
-                if ev != v:
-                    up[k] = ev
+                if self.has_choices(k):
+                    up[k] = v
+                else:
+                    ev = self.eval(v, context=context, fLOG=fLOG)
+                    if ev != v:
+                        up[k] = ev
+
             if len(up) > 0:
                 for k, v in up.items():
                     res.__dict__[k] = v