diff --git a/lisp/url/url-http.el b/lisp/url/url-http.el
index 7156e6f..860e652 100644
--- a/lisp/url/url-http.el
+++ b/lisp/url/url-http.el
@@ -235,7 +235,7 @@ url-http-create-request
 			      'url-http-proxy-basic-auth-storage))
 			 (url-get-authentication url-http-proxy nil 'any nil))))
 	 (real-fname (url-filename url-http-target-url))
-	 (host (url-host url-http-target-url))
+	 (host (url-http--encode-string (url-host url-http-target-url)))
 	 (auth (if (cdr-safe (assoc "Authorization" url-http-extra-headers))
 		   nil
 		 (url-get-authentication (or
@@ -278,7 +278,8 @@ url-http-create-request
           (concat
              ;; The request
              (or url-http-method "GET") " "
-             (if using-proxy (url-recreate-url url-http-target-url) real-fname)
+             (url-http--encode-string
+              (if using-proxy (url-recreate-url url-http-target-url) real-fname))
              " HTTP/" url-http-version "\r\n"
              ;; Version of MIME we speak
              "MIME-Version: 1.0\r\n"
@@ -360,6 +361,11 @@ url-http-create-request
     (url-http-debug "Request is: \n%s" request)
     request))
 
+(defun url-http--encode-string (s)
+  (if (multibyte-string-p s)
+      (encode-coding-string s 'us-ascii)
+    s))
+
 ;; Parsing routines
 (defun url-http-clean-headers ()
   "Remove trailing \r from header lines.