diff --git a/daphne/utils.py b/daphne/utils.py
index 6c173ea..cd9e86e 100644
--- a/daphne/utils.py
+++ b/daphne/utils.py
@@ -45,9 +45,8 @@ def parse_x_forwarded_for(headers,
     # Lowercase all header names in the dict
     headers = {name.lower(): values for name, values in headers.items()}
 
-    # Make sure header names and values are bytes
+    # Make sure header names are bytes (values are checked in header_value)
     assert all(isinstance(name, bytes) for name in headers.keys())
-    assert all(isinstance(value, bytes) for value in headers.values())
 
     address_header_name = address_header_name.lower().encode("utf-8")
     result = original