diff --git a/Lib/http/client.py b/Lib/http/client.py
index 2799c07..34c098d 100644
--- a/Lib/http/client.py
+++ b/Lib/http/client.py
@@ -917,6 +917,8 @@
         for i, one_value in enumerate(values):
             if hasattr(one_value, 'encode'):
                 values[i] = one_value.encode('ascii')
+            elif isinstance(one_value, int):
+                values[i] = str(one_value).encode('ascii')
         value = b'\r\n\t'.join(values)
         header = header + b': ' + value
         self._output(header)