diff --git a/warcio/capture_http.py b/warcio/capture_http.py
index d83cb277..ab740748 100644
--- a/warcio/capture_http.py
+++ b/warcio/capture_http.py
@@ -165,11 +165,11 @@ def set_remote_ip(self, remote_ip):
 
     def write_request(self, buff):
         if self.started_req:
-            self.request_out.write(buff)
+            self.request_out.write(buff.encode())
 
     def write_response(self, buff):
         if self.started_req:
-            self.response_out.write(buff)
+            self.response_out.write(buff.encode())
 
     def _create_record(self, out, record_type):
         length = out.tell()