diff --git a/scheme/httpd/core.scm b/scheme/httpd/core.scm
index 9a553b5..78c8cf8 100644
--- a/scheme/httpd/core.scm
+++ b/scheme/httpd/core.scm
@@ -19,11 +19,6 @@
 ;;; described in RFC 2616 19.6. See RFC 1945 for the specification of
 ;;; HTTP/1.0 and 0.9.
 
-(define http-version-string 
-  (string-append "HTTP/" 
-		 (number->string (car http-version)) 
-		 "."
-		 (number->string (cdr http-version))))
 
 (define (httpd options)
   (let ((port (httpd-options-port options))
@@ -171,6 +166,7 @@
 	 (lambda ()
 	   (let ((initial-req (parse-http-request sock options)))
 	     (check-major-http-version initial-req)
+	     (check-host-header initial-req)
 	     (let redirect-loop ((req initial-req)) 
 	       (let response-loop ((response ((httpd-options-request-handler options)
 					      (http-url-path (request-url req))
@@ -269,6 +265,11 @@
   (if (> (car (request-version req)) (car http-version))
       (http-error (status-code version-not-supp) req)))
 
+(define (check-host-header req)
+  (if (not (version< (request-version req) '(1 . 1)))
+      (or (get-header (request-headers req) 'host)
+	  (http-error (status-code bad-request) req "Missing Host header"))))
+
 
 ;;; Split string into a list of whitespace-separated strings.
 ;;; This could have been trivially defined in scsh as (field-splitter " \t\n")
@@ -289,7 +290,7 @@
        (else '()))))
 
 (define (send-http-headers response port)
-  (display http-version-string port)
+  (display (version->string http-version) port)
   (write-char #\space port)
   (display (status-code-number (response-code response)) port)
   (write-char #\space port)