diff --git a/src/dispextern.h b/src/dispextern.h
index 79a97f6d6d..fb556c906d 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -3589,7 +3589,6 @@ enum resource_types
   RES_TYPE_BOOLEAN_NUMBER
 };
 
-extern Display_Info *check_x_display_info (Lisp_Object);
 extern Lisp_Object gui_display_get_arg (union display_info, Lisp_Object,
                                         Lisp_Object, const char *,
                                         const char *, enum resource_types);
diff --git a/src/nsfns.m b/src/nsfns.m
index 5968b38e28..b5285ce828 100644
--- a/src/nsfns.m
+++ b/src/nsfns.m
@@ -72,40 +72,17 @@ Updated by Christian Limpach (chris@nice.ch)
    nil stands for the selected frame--or, if that is not a Nextstep frame,
    the first Nextstep display on the list.  */
 
-static struct ns_display_info *
+struct ns_display_info *
 check_ns_display_info (Lisp_Object object)
 {
-  struct ns_display_info *dpyinfo = NULL;
-
-  if (NILP (object))
-    {
-      struct frame *sf = XFRAME (selected_frame);
-
-      if (FRAME_NS_P (sf) && FRAME_LIVE_P (sf))
-	dpyinfo = FRAME_DISPLAY_INFO (sf);
-      else if (x_display_list != 0)
-	dpyinfo = x_display_list;
-      else
-        error ("Nextstep windows are not in use or not initialized");
-    }
-  else if (TERMINALP (object))
-    {
-      struct terminal *t = decode_live_terminal (object);
-
-      if (t->type != output_ns)
-        error ("Terminal %d is not a Nextstep display", t->id);
-
-      dpyinfo = t->display_info.ns;
-    }
-  else if (STRINGP (object))
-    dpyinfo = ns_display_info_for_name (object);
+  if (STRINGP (object))
+    return ns_display_info_for_name (object);
   else
     {
-      struct frame *f = decode_window_system_frame (object);
-      dpyinfo = FRAME_DISPLAY_INFO (f);
-    }
+      union display_info dpyinfo_u = decode_display_info (object, output_ns);
 
-  return dpyinfo;
+      return dpyinfo_u.ns;
+    }
 }
 
 
@@ -2221,14 +2198,6 @@ Frames are listed from topmost (first) to bottommost (last).  */)
 
    ========================================================================== */
 
-/* called from frame.c */
-struct ns_display_info *
-check_x_display_info (Lisp_Object frame)
-{
-  return check_ns_display_info (frame);
-}
-
-
 void
 x_set_scroll_bar_default_width (struct frame *f)
 {
diff --git a/src/w32fns.c b/src/w32fns.c
index 4873e7866c..c6da1cef73 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -288,44 +288,26 @@ typedef BOOL (WINAPI *IsDebuggerPresent_Proc) (void);
 /* stdin, from w32console.c */
 extern HANDLE keyboard_handle;
 
+
+static struct w32_display_info *w32_display_info_for_name (Lisp_Object);
+
 /* Let the user specify a display with a frame.
    nil stands for the selected frame--or, if that is not a w32 frame,
    the first display on the list.  */
 
-struct w32_display_info *
-check_x_display_info (Lisp_Object object)
+static struct w32_display_info *
+check_w32_display_info (Lisp_Object object)
 {
-  if (NILP (object))
-    {
-      struct frame *sf = XFRAME (selected_frame);
-
-      if (FRAME_W32_P (sf) && FRAME_LIVE_P (sf))
-	return FRAME_DISPLAY_INFO (sf);
-      else
-	return &one_w32_display_info;
-    }
-  else if (TERMINALP (object))
-    {
-      struct terminal *t = decode_live_terminal (object);
-
-      if (t->type != output_w32)
-	error ("Terminal %d is not a W32 display", t->id);
-
-      return t->display_info.w32;
-    }
-  else if (STRINGP (object))
-    return x_display_info_for_name (object);
+  if (STRINGP (object))
+    return w32_display_info_for_name (object);
   else
     {
-      struct frame *f;
+      union display_info dpyinfo_u = decode_display_info (object, output_w32);
 
-      CHECK_LIVE_FRAME (object);
-      f = XFRAME (object);
-      if (! FRAME_W32_P (f))
-	error ("Non-W32 frame used");
-      return FRAME_DISPLAY_INFO (f);
+      return dpyinfo_u.w32;
     }
 }
+
 
 /* Return the Emacs frame-object corresponding to an w32 window.
    It could be the frame's main window or an icon window.  */
@@ -5724,7 +5706,7 @@ DEFUN ("x-create-frame", Fx_create_frame, Sx_create_frame,
                                    parameters, Qdisplay, 0, 0, RES_TYPE_STRING);
   if (EQ (display, Qunbound))
     display = Qnil;
-  dpyinfo = check_x_display_info (display);
+  dpyinfo = check_w32_display_info (display);
   kb = dpyinfo->terminal->kboard;
 
   if (!dpyinfo->terminal->name)
@@ -6159,7 +6141,7 @@ DEFUN ("xw-display-color-p", Fxw_display_color_p, Sxw_display_color_p, 0, 1, 0,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
 
   if ((dpyinfo->n_planes * dpyinfo->n_cbits) <= 2)
     return Qnil;
@@ -6172,7 +6154,7 @@ DEFUN ("x-display-grayscale-p", Fx_display_grayscale_p,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
 
   if ((dpyinfo->n_planes * dpyinfo->n_cbits) <= 1)
     return Qnil;
@@ -6185,7 +6167,7 @@ DEFUN ("x-display-pixel-width", Fx_display_pixel_width,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
 
   return make_fixnum (x_display_pixel_width (dpyinfo));
 }
@@ -6195,7 +6177,7 @@ DEFUN ("x-display-pixel-height", Fx_display_pixel_height,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
 
   return make_fixnum (x_display_pixel_height (dpyinfo));
 }
@@ -6205,7 +6187,7 @@ DEFUN ("x-display-planes", Fx_display_planes, Sx_display_planes,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
 
   return make_fixnum (dpyinfo->n_planes * dpyinfo->n_cbits);
 }
@@ -6215,7 +6197,7 @@ DEFUN ("x-display-color-cells", Fx_display_color_cells, Sx_display_color_cells,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
   int cap;
 
   /* Don't use NCOLORS: it returns incorrect results under remote
@@ -6262,7 +6244,7 @@ DEFUN ("x-display-mm-height", Fx_display_mm_height,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
   HDC hdc;
   double mm_per_pixel;
 
@@ -6278,7 +6260,7 @@ DEFUN ("x-display-mm-width", Fx_display_mm_width, Sx_display_mm_width, 0, 1, 0,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
   HDC hdc;
   double mm_per_pixel;
 
@@ -6303,7 +6285,7 @@ DEFUN ("x-display-visual-class", Fx_display_visual_class,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
   Lisp_Object result = Qnil;
 
   if (dpyinfo->has_palette)
@@ -6505,7 +6487,7 @@ If omitted or nil, that stands for the selected frame's display.
 Internal use only, use `display-monitor-attributes-list' instead.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
   Lisp_Object attributes_list;
 
   block_input ();
@@ -6558,8 +6540,8 @@ x_screen_planes (register struct frame *f)
 /* Return the display structure for the display named NAME.
    Open a new connection if necessary.  */
 
-struct w32_display_info *
-x_display_info_for_name (Lisp_Object name)
+static struct w32_display_info *
+w32_display_info_for_name (Lisp_Object name)
 {
   struct w32_display_info *dpyinfo;
 
@@ -6670,7 +6652,7 @@ DEFUN ("x-close-connection", Fx_close_connection,
        doc: /* SKIP: real doc in xfns.c.  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
 
   if (dpyinfo->reference_count > 0)
     error ("Display still has frames on it");
@@ -8979,7 +8961,7 @@ return the child frames of that frame in Z (stacking) order.
 Frames are listed from topmost (first) to bottommost (last).  */)
   (Lisp_Object display)
 {
-  struct w32_display_info *dpyinfo = check_x_display_info (display);
+  struct w32_display_info *dpyinfo = check_w32_display_info (display);
   HWND window;
 
   block_input ();
diff --git a/src/w32term.h b/src/w32term.h
index 6cc0cedc14..e4ebb620a0 100644
--- a/src/w32term.h
+++ b/src/w32term.h
@@ -239,8 +239,6 @@ extern int menubar_in_use;
 
 extern struct frame *x_window_to_frame (struct w32_display_info *, HWND);
 
-struct w32_display_info *x_display_info_for_name (Lisp_Object);
-
 /* also defined in xterm.h XXX: factor out to common header */
 
 extern struct w32_display_info *w32_term_init (Lisp_Object,
diff --git a/src/xfns.c b/src/xfns.c
index 5d92ab9086..7e5e5985eb 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -158,37 +158,15 @@ static void set_up_x_back_buffer (struct frame *f);
 struct x_display_info *
 check_x_display_info (Lisp_Object object)
 {
-  struct x_display_info *dpyinfo = NULL;
-
-  if (NILP (object))
-    {
-      struct frame *sf = XFRAME (selected_frame);
-
-      if (FRAME_X_P (sf) && FRAME_LIVE_P (sf))
-	dpyinfo = FRAME_DISPLAY_INFO (sf);
-      else if (x_display_list != 0)
-	dpyinfo = x_display_list;
-      else
-	error ("X windows are not in use or not initialized");
-    }
-  else if (TERMINALP (object))
-    {
-      struct terminal *t = decode_live_terminal (object);
-
-      if (t->type != output_x_window)
-        error ("Terminal %d is not an X display", t->id);
-
-      dpyinfo = t->display_info.x;
-    }
-  else if (STRINGP (object))
-    dpyinfo = x_display_info_for_name (object);
+  if (STRINGP (object))
+    return x_display_info_for_name (object);
   else
     {
-      struct frame *f = decode_window_system_frame (object);
-      dpyinfo = FRAME_DISPLAY_INFO (f);
-    }
+      union display_info dpyinfo_u = decode_display_info (object,
+                                                          output_x_window);
 
-  return dpyinfo;
+      return dpyinfo_u.x;
+    }
 }
 
 /* Return the screen positions and offsets of frame F.
diff --git a/src/xterm.h b/src/xterm.h
index da95926eda..6548b0ef8c 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -497,6 +497,7 @@ extern bool use_xim;
 extern struct x_display_info *x_display_list;
 
 extern struct x_display_info *x_display_info_for_display (Display *);
+extern struct x_display_info *check_x_display_info (Lisp_Object);
 extern struct frame *x_top_window_to_frame (struct x_display_info *, int);
 extern struct x_display_info *x_term_init (Lisp_Object, char *, char *);
 extern bool x_display_ok (const char *);