diff --git a/optimizely/project_config.py b/optimizely/project_config.py
index fbd4d41f..f80b389a 100644
--- a/optimizely/project_config.py
+++ b/optimizely/project_config.py
@@ -40,7 +40,7 @@ def __init__(self, datafile, logger, error_handler):
         """
 
         config = json.loads(datafile)
-        self._datafile = str(datafile)
+        self._datafile = datafile.encode('utf-8')
         self.logger = logger
         self.error_handler = error_handler
         self.version = config.get('version')