1 files changed, 5 insertions, 1 deletions

diff --git a/lisp/simple.el b/lisp/simple.el
index 6aae21a3f0c..f9839826ff6 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -3491,7 +3491,11 @@ in the definition is used to check that VALUE is valid."
       (unless (widget-apply type :match val)
         (error "Value `%S' does not match type %S of %S"
                val (car type) var))))
-  (set var val))
+  (set var val)
+
+  ;; Force a thorough redisplay for the case that the variable
+  ;; has an effect on the display, like `tab-width' has.
+  (force-mode-line-update))
 
 ;; Define the major mode for lists of completions.