diff --git a/module/web/client.scm b/module/web/client.scm
index a08c4203c..9273a45ad 100644
--- a/module/web/client.scm
+++ b/module/web/client.scm
@@ -320,7 +320,8 @@ host name without trailing dot."
   (read-response port))
 
 (define* (open-socket-for-uri uri-or-string
-                              #:key (verify-certificate? #t))
+                              #:key (verify-certificate? #t)
+                              (flags 0))
   "Return an open input/output port for a connection to URI-OR-STRING.
 When VERIFY-CERTIFICATE? is true, verify HTTPS server certificates."
   (define uri
@@ -373,10 +374,18 @@ When VERIFY-CERTIFICATE? is true, verify HTTPS server certificates."
     (when (and https? (current-https-proxy))
       (setup-http-tunnel s uri))
 
-    (if https?
-        (tls-wrap s (uri-host uri)
-                  #:verify-certificate? verify-certificate?)
-        s)))
+    (let ((port (if https?
+                    (tls-wrap s (uri-host uri)
+                              #:verify-certificate? verify-certificate?)
+                    s)))
+      (unless (zero? flags)
+        ;; FLAGS might contain O_NONBLOCK.  Thus, set it as a last step
+        ;; because 'handshake' otherwise throws an exception for
+        ;; GNUTLS_E_AGAIN.
+        (let ((initial-flags (fcntl s F_GETFL)))
+          (fcntl s F_SETFL (logior initial-flags flags))))
+
+      port)))
 
 (define (extend-request r k v . additional)
   (let ((r (set-field r (request-headers)