1 files changed, 3 insertions, 2 deletions

diff --git a/lisp/window.el b/lisp/window.el
index 67e39ecc9dd..54ac8115727 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -4851,8 +4851,9 @@ frame.  The selected window is not changed by this function."
               (set-window-parameter (window-parent new) 'window-atom t))
             (set-window-parameter new 'window-atom t)))
 
-          ;; Sanitize sizes.
-          (window--sanitize-window-sizes frame horizontal)
+          ;; Sanitize sizes unless SIZE was specified.
+          (unless size
+            (window--sanitize-window-sizes frame horizontal))
 
           (run-window-configuration-change-hook frame)
           (run-window-scroll-functions new)