diff --git a/lib/matplotlib/mlab.py b/lib/matplotlib/mlab.py
index 57fc4995f440..09c698bdaa95 100644
--- a/lib/matplotlib/mlab.py
+++ b/lib/matplotlib/mlab.py
@@ -2613,7 +2613,7 @@ def mapped_r2field(name):
 
     if jointype != 'inner' and defaults is not None:
         # fill in the defaults enmasse
-        newrec_fields = list(six.iterkeys(newrec.dtype.fields.keys))
+        newrec_fields = list(six.iterkeys(newrec.dtype.fields))
         for k, v in six.iteritems(defaults):
             if k in newrec_fields:
                 newrec[k] = v