diff --git a/lib/matplotlib/afm.py b/lib/matplotlib/afm.py
index 5a2cffbfbb7b..1b5f4d5f6a0d 100644
--- a/lib/matplotlib/afm.py
+++ b/lib/matplotlib/afm.py
@@ -19,7 +19,7 @@
     ...                         'fonts', 'afm', 'ptmr8a.afm')
     >>>
     >>> from matplotlib.afm import AFM
-    >>> with open(afm_fname) as fh:
+    >>> with open(afm_fname, 'rb') as fh:
     ...     afm = AFM(fh)
     >>> afm.string_width_height('What the heck?')
     (6220.0, 694)