diff --git a/calc.el b/calc.el
index 4bebd5f..90dcce6 100644
--- a/calc.el
+++ b/calc.el
@@ -1472,6 +1472,7 @@ commands given here will actually operate on the *Calculator* stack."
       (and (windowp full-display)
            (window-point full-display)
            (select-window full-display))
+      (set-window-dedicated-p nil t)
       (calc-check-defines)
       (when (and calc-said-hello interactive)
         (sit-for 2)
@@ -2136,7 +2137,8 @@ the United States."
               (if calc-trail-window-hook
                   (run-hooks 'calc-trail-window-hook)
                 (let ((w (split-window nil (/ (* (window-width) 2) 3) t)))
-                  (set-window-buffer w calc-trail-buffer)))
+                  (set-window-buffer w calc-trail-buffer)
+                  (set-window-dedicated-p w t)))
               (calc-wrapper
                (setq overlay-arrow-string calc-trail-overlay
                      overlay-arrow-position calc-trail-pointer)