1 files changed, 25 insertions, 24 deletions

diff --git a/lisp/faces.el b/lisp/faces.el
index 4a7d951aeac..2a817eba106 100644
--- a/lisp/faces.el
+++ b/lisp/faces.el
@@ -1457,30 +1457,31 @@ examine the brightness for you."
 
 (defun frame-set-background-mode (frame)
   "Set up the `background-mode' and `display-type' frame parameters for FRAME."
-  (let ((bg-resource (x-get-resource ".backgroundMode"
-                                     "BackgroundMode"))
-        (params (frame-parameters frame))
-        (bg-mode))
-    (setq bg-mode
-          (cond (frame-background-mode)
-                (bg-resource (intern (downcase bg-resource)))
-                ((< (apply '+ (x-color-values
-                               (cdr (assq 'background-color params))
-                               frame))
-                    ;; Just looking at the screen,
-                    ;; colors whose values add up to .6 of the white total
-                    ;; still look dark to me.
-                    (* (apply '+ (x-color-values "white" frame)) .6))
-                 'dark)
-                (t 'light)))
-    (modify-frame-parameters frame
-                             (list (cons 'background-mode bg-mode)
-                                   (cons 'display-type
-                                         (cond ((x-display-color-p frame)
-                                                'color)
-                                               ((x-display-grayscale-p frame)
-                                                'grayscale)
-                                               (t 'mono)))))))
+  (unless (memq (framep frame) '(t pc))
+    (let ((bg-resource (x-get-resource ".backgroundMode"
+                                       "BackgroundMode"))
+          (params (frame-parameters frame))
+          (bg-mode))
+      (setq bg-mode
+            (cond (frame-background-mode)
+                  (bg-resource (intern (downcase bg-resource)))
+                  ((< (apply '+ (x-color-values
+                                 (cdr (assq 'background-color params))
+                                 frame))
+                      ;; Just looking at the screen,
+                      ;; colors whose values add up to .6 of the white total
+                      ;; still look dark to me.
+                      (* (apply '+ (x-color-values "white" frame)) .6))
+                   'dark)
+                  (t 'light)))
+      (modify-frame-parameters frame
+                               (list (cons 'background-mode bg-mode)
+                                     (cons 'display-type
+                                           (cond ((x-display-color-p frame)
+                                                  'color)
+                                                 ((x-display-grayscale-p frame)
+                                                  'grayscale)
+                                                 (t 'mono))))))))
 
 ;; Update a frame's faces when we change its default font.
 (defun frame-update-faces (frame) nil)