diff --git a/scheme/httpd/core.scm b/scheme/httpd/core.scm
index 3862616..f64178b 100644
--- a/scheme/httpd/core.scm
+++ b/scheme/httpd/core.scm
@@ -350,7 +350,7 @@
 (define (send-http-header-fields headers port)
   (for-each (lambda (pair)
 	      (display (car pair) port)
-	      (display ": " port)
+	      (write-char #\: port)
 	      (display (cdr pair) port)
 	      (write-crlf port))
 	    headers))