2 files changed, 13 insertions, 1 deletions

diff --git a/lisp/url/ChangeLog b/lisp/url/ChangeLog
index 81096cfb800..21a779f85b3 100644
--- a/lisp/url/ChangeLog
+++ b/lisp/url/ChangeLog
@@ -1,3 +1,8 @@
+2014-10-07  Eli Zaretskii  <eliz@gnu.org>
+
+        * url-http.el (url-http-create-request): Recheck zlib availability
+        on windows-nt each time it might be required.  (Bug#18650)
+
 2014-09-28  Ulf Jasper  <ulf.jasper@web.de>
 
         * url-gw.el (url-open-stream): New optional parameter
diff --git a/lisp/url/url-http.el b/lisp/url/url-http.el
index 9a874c25ce0..f9fbea1ba74 100644
--- a/lisp/url/url-http.el
+++ b/lisp/url/url-http.el
@@ -313,7 +313,14 @@ request.")
                  (concat
                   "From: " url-personal-mail-address "\r\n"))
              ;; Encodings we understand
-             (if url-mime-encoding-string
+             (if (or url-mime-encoding-string
+                     ;; MS-Windows loads zlib dynamically, so recheck
+                     ;; in case they made it available since
+                     ;; initialization in url-vars.el.
+                     (and (eq 'system-type 'windows-nt)
+                          (fboundp 'zlib-available-p)
+                          (zlib-available-p)
+                          (setq url-mime-encoding-string "gzip")))
                  (concat
                   "Accept-encoding: " url-mime-encoding-string "\r\n"))
              (if url-mime-charset-string