diff --git a/collects/mred/private/wx/win32/utils.rkt b/collects/mred/private/wx/win32/utils.rkt
index f100116b..727bc736 100644
--- a/collects/mred/private/wx/win32/utils.rkt
+++ b/collects/mred/private/wx/win32/utils.rkt
@@ -19,8 +19,8 @@
 
               GetLastError
 
-              GetWindowLongW
-              SetWindowLongW
+              GetWindowLongPtrW
+              SetWindowLongPtrW
               SendMessageW SendMessageW/str
               GetSysColor GetRValue GetGValue GetBValue make-COLORREF
               CreateBitmap
@@ -67,8 +67,8 @@
   (error who "call failed (~s)"
          (GetLastError)))
 
-(define-user32 GetWindowLongW (_wfun _HWND _int -> _pointer))
-(define-user32 SetWindowLongW (_wfun _HWND _int _pointer -> _pointer))
+(define-user32 GetWindowLongPtrW (_wfun _HWND _int -> _pointer))
+(define-user32 SetWindowLongPtrW (_wfun _HWND _int _pointer -> _pointer))
 
 (define-user32 SendMessageW (_wfun _HWND _UINT _WPARAM _LPARAM -> _LRESULT))
 (define-user32 SendMessageW/str (_wfun _HWND _UINT _WPARAM _string/utf-16 -> _LRESULT)
diff --git a/collects/mred/private/wx/win32/wndclass.rkt b/collects/mred/private/wx/win32/wndclass.rkt
index 8bcf8f4d..880209d6 100644
--- a/collects/mred/private/wx/win32/wndclass.rkt
+++ b/collects/mred/private/wx/win32/wndclass.rkt
@@ -37,21 +37,21 @@
 (define (register-hwnd! hwnd)
   (hash-set! all-hwnds (cast hwnd _pointer _intptr) #t)
   (let ([c (malloc-immobile-cell (vector #f #f #f))])
-    (void (SetWindowLongW hwnd GWLP_USERDATA c))))
+    (void (SetWindowLongPtrW hwnd GWLP_USERDATA c))))
   
 (define (set-hwnd-wx! hwnd wx)
-  (let* ([c (GetWindowLongW hwnd GWLP_USERDATA)]
+  (let* ([c (GetWindowLongPtrW hwnd GWLP_USERDATA)]
          [v (ptr-ref c _racket)])
     (vector-set! v 0 (make-weak-box wx))))
 
 (define (set-hwnd-ctlproc! hwnd save-ptr ctlproc)
-  (let* ([c (GetWindowLongW hwnd GWLP_USERDATA)]
+  (let* ([c (GetWindowLongPtrW hwnd GWLP_USERDATA)]
          [v (ptr-ref c _racket)])
     (vector-set! v 1 ctlproc)
     (vector-set! v 2 save-ptr)))
 
 (define (hwnd->wx hwnd)
-  (let ([c (GetWindowLongW hwnd GWLP_USERDATA)])
+  (let ([c (GetWindowLongPtrW hwnd GWLP_USERDATA)])
     (and c (let ([v (ptr-ref c _racket)])
              (and v
                   (let ([wb (vector-ref v 0)])
@@ -67,12 +67,12 @@
           wx))))
 
 (define (hwnd->ctlproc hwnd)
-  (let ([c (GetWindowLongW hwnd GWLP_USERDATA)])
+  (let ([c (GetWindowLongPtrW hwnd GWLP_USERDATA)])
     (and c (let ([v (ptr-ref c _racket)])
              (and v (vector-ref v 1))))))
 
 (define (hwnd->ctlproc-fptr hwnd)
-  (let ([c (GetWindowLongW hwnd GWLP_USERDATA)])
+  (let ([c (GetWindowLongPtrW hwnd GWLP_USERDATA)])
     (and c (let ([v (ptr-ref c _racket)])
              (and v (vector-ref v 2))))))
 
@@ -82,10 +82,10 @@
 
 ;; call in atomic mode:
 (define (unregister-hwnd! hwnd)
-  (let ([c (GetWindowLongW hwnd GWLP_USERDATA)])
+  (let ([c (GetWindowLongPtrW hwnd GWLP_USERDATA)])
     (when c
       (free-immobile-cell c)
-      (SetWindowLongW hwnd GWLP_USERDATA #f))
+      (SetWindowLongPtrW hwnd GWLP_USERDATA #f))
     (hash-remove! all-hwnds (cast hwnd _pointer _intptr))))
 
 ;; ----------------------------------------
@@ -122,7 +122,7 @@
   (let ([default-ctlproc (hwnd->ctlproc w)])
     (if (= msg WM_DESTROY)
         (begin
-          (SetWindowLongW w GWLP_WNDPROC (hwnd->ctlproc-fptr w))
+          (SetWindowLongPtrW w GWLP_WNDPROC (hwnd->ctlproc-fptr w))
           (unregister-hwnd! w)
           (default-ctlproc w msg wParam lParam))
         (let ([wx (hwnd->wx w)])
@@ -135,10 +135,10 @@
 (define control_proc (function-ptr control-proc _WndProc))
 
 (define (subclass-control hwnd)
-  (let* ([fptr (GetWindowLongW hwnd GWLP_WNDPROC)]
+  (let* ([fptr (GetWindowLongPtrW hwnd GWLP_WNDPROC)]
          [old-control-proc (function-ptr fptr _WndProc)])
     (set-hwnd-ctlproc! hwnd fptr old-control-proc)
-    (SetWindowLongW hwnd GWLP_WNDPROC control_proc)))
+    (SetWindowLongPtrW hwnd GWLP_WNDPROC control_proc)))
 
 
 (define _DialogProc (_wfun _HWND _UINT _WPARAM _LPARAM -> _INT_PTR))