diff --git a/coverage/config.py b/coverage/config.py
index d16c9d6e3..6d336d1f9 100644
--- a/coverage/config.py
+++ b/coverage/config.py
@@ -325,7 +325,7 @@ def from_file(self, filename, our_file):
 
         if used:
             self.config_file = os.path.abspath(filename)
-            with open(filename) as f:
+            with open(filename, "rb") as f:
                 self._config_contents = f.read()
 
         return used