diff --git a/config.el b/config.el
index 01ae3f6..c7f4242 100644
--- a/config.el
+++ b/config.el
@@ -1759,11 +1759,13 @@ Baikal uses Digest auth. url-digest-auth-storage stores HA1 = MD5(user:realm:pas
            (realm "BaikalDAV")
            (server "cal.apps.sukany.cz:443"))
       (when pass
+        ;; url-digest-auth-storage format: (("server:port" ("realm" user ha1) ...) ...)
+        ;; (cdr realm-entry) must be a list (user ha1), NOT a bare string.
         (let ((ha1 (md5 (concat user ":" realm ":" pass)))
               (existing (assoc server url-digest-auth-storage)))
           (if existing
-              (setcdr existing (list (cons realm ha1)))
-            (push (list server (cons realm ha1))
+              (setcdr existing (list (list realm user ha1)))
+            (push (list server (list realm user ha1))
                   url-digest-auth-storage))))))
 
   (defun my/org-caldav-sync ()