diff --git a/dlls/msvfw32/mciwnd.c b/dlls/msvfw32/mciwnd.c
index 61b13aaeb8..ff8a0369df 100644
--- a/dlls/msvfw32/mciwnd.c
+++ b/dlls/msvfw32/mciwnd.c
@@ -449,7 +449,7 @@ static LRESULT WINAPI MCIWndProc(HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lPa
 
     TRACE("%p %04x %08lx %08lx\n", hWnd, wMsg, wParam, lParam);
 
-    mwi = (MCIWndInfo*)GetWindowLongW(hWnd, 0);
+    mwi = (MCIWndInfo*)GetWindowLongPtrW(hWnd, 0);
     if (!mwi && wMsg != WM_CREATE)
         return DefWindowProcW(hWnd, wMsg, wParam, lParam);
 
@@ -568,7 +568,7 @@ static LRESULT WINAPI MCIWndProc(HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lPa
             hCursor = SetCursor(hCursor);
 
             mci_open.lpstrElementName = (LPWSTR)lParam;
-            wsprintfW(aliasW, formatW, (int)hWnd + 1);
+            wsprintfW(aliasW, formatW, HandleToLong(hWnd) + 1);
             mci_open.lpstrAlias = aliasW;
             mwi->lasterror = mciSendCommandW(mwi->mci, MCI_OPEN,
                                              MCI_OPEN_ELEMENT | MCI_OPEN_ALIAS | MCI_WAIT,
@@ -588,7 +588,7 @@ static LRESULT WINAPI MCIWndProc(HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lPa
             }
 
             mwi->mci = mci_open.wDeviceID;
-            mwi->alias = (int)hWnd + 1;
+            mwi->alias = HandleToLong(hWnd) + 1;
 
             mwi->lpName = HeapAlloc(GetProcessHeap(), 0, (strlenW((LPWSTR)lParam) + 1) * sizeof(WCHAR));
             strcpyW(mwi->lpName, (LPWSTR)lParam);