diff --git a/lisp/gnus-icalendar.el b/lisp/gnus-icalendar.el
index 56c56f3dd466975da7b23edd257058ff63fb8bfd..12455aff8622101eb93f4378b0564c4f8dfcc0fd 100644
--- a/lisp/gnus-icalendar.el
+++ b/lisp/gnus-icalendar.el
@@ -52,6 +52,22 @@
 ;;; ical-event
 ;;;
 
+(defgroup gnus-icalendar nil
+  "Settings for inline display of iCalendar invitations."
+  :group 'gnus-article
+  :prefix "gnus-icalendar-")
+
+(defcustom gnus-icalendar-custom-tz nil
+  "Translate non-standard timezone names.
+
+Invitations might show with wrong start/end times when the ical
+timestamps contain non-standard timezone names.  If this happens,
+you can tell gnus to translate the timezone name to something
+gnus will recognize."
+  :type '(alist :key-type string :value-type string)
+  :group 'gnus-icalendar)
+
+
 (defclass gnus-icalendar-event ()
   ((organizer :initarg :organizer
               :accessor gnus-icalendar-event:organizer
@@ -143,7 +159,9 @@
 (defun gnus-icalendar-event--decode-datefield (ical field)
   (let* ((date (icalendar--get-event-property ical field))
          (date-props (icalendar--get-event-property-attributes ical field))
-         (tz (plist-get date-props 'TZID)))
+         (tzid (plist-get date-props 'TZID))
+         (tz (or (cdr (assoc tzid gnus-icalendar-custom-tz))
+                 tzid)))
 
     (date-to-time (timezone-make-date-arpa-standard date nil tz))))
 
@@ -639,11 +657,6 @@ is searched."
 ;;; gnus-icalendar
 ;;;
 
-(defgroup gnus-icalendar nil
-  "Settings for inline display of iCalendar invitations."
-  :group 'gnus-article
-  :prefix "gnus-icalendar-")
-
 (defcustom gnus-icalendar-reply-bufname "*CAL*"
   "Buffer used for building iCalendar invitation reply."
   :type '(string)