diff --git a/ipn/desktop/mksyscall.go b/ipn/desktop/mksyscall.go
index 305138468..b7af12366 100644
--- a/ipn/desktop/mksyscall.go
+++ b/ipn/desktop/mksyscall.go
@@ -11,8 +11,6 @@ package desktop
 //sys registerClassEx(windowClass *_WNDCLASSEX) (atom uint16, err error) [atom==0] = user32.RegisterClassExW
 //sys createWindowEx(dwExStyle uint32, lpClassName *uint16, lpWindowName *uint16, dwStyle uint32, x int32, y int32, nWidth int32, nHeight int32, hWndParent windows.HWND, hMenu windows.Handle, hInstance windows.Handle, lpParam unsafe.Pointer) (hWnd windows.HWND, err error) [hWnd==0] = user32.CreateWindowExW
 //sys defWindowProc(hwnd windows.HWND, msg uint32, wparam uintptr, lparam uintptr) (res uintptr) = user32.DefWindowProcW
-//sys setWindowLongPtr(hwnd windows.HWND, index int32, newLong uintptr) (res uintptr, err error) [res==0 && e1!=0] = user32.SetWindowLongPtrW
-//sys getWindowLongPtr(hwnd windows.HWND, index int32) (res uintptr, err error) [res==0 && e1!=0] = user32.GetWindowLongPtrW
 //sys sendMessage(hwnd windows.HWND, msg uint32, wparam uintptr, lparam uintptr) (res uintptr) = user32.SendMessageW
 //sys getMessage(lpMsg *_MSG, hwnd windows.HWND, msgMin uint32, msgMax uint32) (ret int32) = user32.GetMessageW
 //sys translateMessage(lpMsg *_MSG) (res bool) = user32.TranslateMessage
diff --git a/ipn/desktop/sessions_windows.go b/ipn/desktop/sessions_windows.go
index b26172d77..83b884228 100644
--- a/ipn/desktop/sessions_windows.go
+++ b/ipn/desktop/sessions_windows.go
@@ -670,3 +670,38 @@ func (cs _WTS_CONNECTSTATE_CLASS) ToSessionStatus() SessionStatus {
 		return ClosedSession
 	}
 }
+
+var (
+	procGetWindowLongPtrW *windows.LazyProc
+	procSetWindowLongPtrW *windows.LazyProc
+)
+
+func init() {
+	// GetWindowLongPtrW and SetWindowLongPtrW are only available on 64-bit platforms.
+	// https://web.archive.org/web/20250414195520/https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getwindowlongptrw
+	if runtime.GOARCH == "386" || runtime.GOARCH == "arm" {
+		procGetWindowLongPtrW = moduser32.NewProc("GetWindowLongW")
+		procSetWindowLongPtrW = moduser32.NewProc("SetWindowLongW")
+	} else {
+		procGetWindowLongPtrW = moduser32.NewProc("GetWindowLongPtrW")
+		procSetWindowLongPtrW = moduser32.NewProc("SetWindowLongPtrW")
+	}
+}
+
+func getWindowLongPtr(hwnd windows.HWND, index int32) (res uintptr, err error) {
+	r0, _, e1 := syscall.Syscall(procGetWindowLongPtrW.Addr(), 2, uintptr(hwnd), uintptr(index), 0)
+	res = uintptr(r0)
+	if res == 0 && e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func setWindowLongPtr(hwnd windows.HWND, index int32, newLong uintptr) (res uintptr, err error) {
+	r0, _, e1 := syscall.Syscall(procSetWindowLongPtrW.Addr(), 3, uintptr(hwnd), uintptr(index), uintptr(newLong))
+	res = uintptr(r0)
+	if res == 0 && e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
diff --git a/ipn/desktop/zsyscall_windows.go b/ipn/desktop/zsyscall_windows.go
index 222ab49e5..535274016 100644
--- a/ipn/desktop/zsyscall_windows.go
+++ b/ipn/desktop/zsyscall_windows.go
@@ -48,11 +48,9 @@ var (
 	procDestroyWindow                      = moduser32.NewProc("DestroyWindow")
 	procDispatchMessageW                   = moduser32.NewProc("DispatchMessageW")
 	procGetMessageW                        = moduser32.NewProc("GetMessageW")
-	procGetWindowLongPtrW                  = moduser32.NewProc("GetWindowLongPtrW")
 	procPostQuitMessage                    = moduser32.NewProc("PostQuitMessage")
 	procRegisterClassExW                   = moduser32.NewProc("RegisterClassExW")
 	procSendMessageW                       = moduser32.NewProc("SendMessageW")
-	procSetWindowLongPtrW                  = moduser32.NewProc("SetWindowLongPtrW")
 	procTranslateMessage                   = moduser32.NewProc("TranslateMessage")
 	procWTSRegisterSessionNotificationEx   = modwtsapi32.NewProc("WTSRegisterSessionNotificationEx")
 	procWTSUnRegisterSessionNotificationEx = modwtsapi32.NewProc("WTSUnRegisterSessionNotificationEx")
@@ -98,15 +96,6 @@ func getMessage(lpMsg *_MSG, hwnd windows.HWND, msgMin uint32, msgMax uint32) (r
 	return
 }
 
-func getWindowLongPtr(hwnd windows.HWND, index int32) (res uintptr, err error) {
-	r0, _, e1 := syscall.Syscall(procGetWindowLongPtrW.Addr(), 2, uintptr(hwnd), uintptr(index), 0)
-	res = uintptr(r0)
-	if res == 0 && e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
 func postQuitMessage(exitCode int32) {
 	syscall.Syscall(procPostQuitMessage.Addr(), 1, uintptr(exitCode), 0, 0)
 	return
@@ -127,15 +116,6 @@ func sendMessage(hwnd windows.HWND, msg uint32, wparam uintptr, lparam uintptr)
 	return
 }
 
-func setWindowLongPtr(hwnd windows.HWND, index int32, newLong uintptr) (res uintptr, err error) {
-	r0, _, e1 := syscall.Syscall(procSetWindowLongPtrW.Addr(), 3, uintptr(hwnd), uintptr(index), uintptr(newLong))
-	res = uintptr(r0)
-	if res == 0 && e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
 func translateMessage(lpMsg *_MSG) (res bool) {
 	r0, _, _ := syscall.Syscall(procTranslateMessage.Addr(), 1, uintptr(unsafe.Pointer(lpMsg)), 0, 0)
 	res = r0 != 0