diff --git a/hgext/fastannotate/context.py b/hgext/fastannotate/context.py
--- a/hgext/fastannotate/context.py
+++ b/hgext/fastannotate/context.py
@@ -156,6 +156,7 @@
     }
 
     def __init__(self, **opts):
+        opts = pycompat.byteskwargs(opts)
         for k, v in self.defaults.iteritems():
             setattr(self, k, opts.get(k, v))