diff --git a/IPython/core/completer.py b/IPython/core/completer.py
index c26780e..73a31e5 100644
--- a/IPython/core/completer.py
+++ b/IPython/core/completer.py
@@ -671,10 +671,12 @@ class IPCompleter(Completer):
 
         return matches
 
-    def _default_arguments_from_docstring(self,doc):
-        """Parse first line of docstring of the
-        form 'min(iterable[, key=func])\n' to find
-        keyword argument names.
+    def _default_arguments_from_docstring(self, doc):
+        """Parse first line of docstring for call signature
+
+        Docstring should be of the form 'min(iterable[, key=func])\n'.
+        I can also parse cython docstring of the form
+        'Minuit.migrad(self, int ncall=10000, resume=True, int nsplit=1)'
         """
         if doc is None:
             return []