diff --git a/dlls/user32/controls.h b/dlls/user32/controls.h
index a16d166bf38..974cf5b890a 100644
--- a/dlls/user32/controls.h
+++ b/dlls/user32/controls.h
@@ -150,7 +150,7 @@ typedef struct
 extern BOOL COMBO_FlipListbox( LPHEADCOMBO, BOOL, BOOL ) DECLSPEC_HIDDEN;
 
 /* Dialog info structure */
-typedef struct
+typedef struct tagDIALOGINFO
 {
     HWND      hwndFocus;   /* Current control with focus */
     HFONT     hUserFont;   /* Dialog font */
@@ -165,9 +165,6 @@ typedef struct
 #define DF_END  0x0001
 #define DF_OWNERENABLED 0x0002
 
-/* offset of DIALOGINFO ptr in dialog extra bytes */
-#define DWLP_WINE_DIALOGINFO (DWLP_USER+sizeof(ULONG_PTR))
-
 extern DIALOGINFO *DIALOG_get_info( HWND hwnd, BOOL create ) DECLSPEC_HIDDEN;
 extern void DIALOG_EnableOwner( HWND hOwner ) DECLSPEC_HIDDEN;
 extern BOOL DIALOG_DisableOwner( HWND hOwner ) DECLSPEC_HIDDEN;
diff --git a/dlls/user32/defdlg.c b/dlls/user32/defdlg.c
index d2305e02498..ee1b58ec461 100644
--- a/dlls/user32/defdlg.c
+++ b/dlls/user32/defdlg.c
@@ -230,8 +230,10 @@ static LRESULT DEFDLG_Proc( HWND hwnd, UINT msg, WPARAM wParam,
             return 1;
         }
         case WM_NCDESTROY:
-            if ((dlgInfo = (DIALOGINFO *)SetWindowLongPtrW( hwnd, DWLP_WINE_DIALOGINFO, 0 )))
+            if (dlgInfo)
             {
+                WND *wndPtr;
+
                 /* Free dialog heap (if created) */
                 if (dlgInfo->hDialogHeap)
                 {
@@ -241,6 +243,10 @@ static LRESULT DEFDLG_Proc( HWND hwnd, UINT msg, WPARAM wParam,
                 if (dlgInfo->hUserFont) DeleteObject( dlgInfo->hUserFont );
                 if (dlgInfo->hMenu) DestroyMenu( dlgInfo->hMenu );
                 HeapFree( GetProcessHeap(), 0, dlgInfo );
+
+                wndPtr = WIN_GetPtr( hwnd );
+                wndPtr->dlgInfo = NULL;
+                WIN_ReleasePtr( wndPtr );
             }
               /* Window clean-up */
             return DefWindowProcA( hwnd, msg, wParam, lParam );
@@ -335,11 +341,18 @@ static LRESULT DEFDLG_Epilog(HWND hwnd, UINT msg, BOOL fResult)
 DIALOGINFO *DIALOG_get_info( HWND hwnd, BOOL create )
 {
     WND* wndPtr;
-    DIALOGINFO* dlgInfo = (DIALOGINFO *)GetWindowLongPtrW( hwnd, DWLP_WINE_DIALOGINFO );
+    DIALOGINFO* dlgInfo;
 
-    if(!dlgInfo && create)
+    wndPtr = WIN_GetPtr( hwnd );
+    if (!wndPtr || wndPtr == WND_OTHER_PROCESS || wndPtr == WND_DESKTOP)
+        return NULL;
+
+    dlgInfo = wndPtr->dlgInfo;
+
+    if (!dlgInfo && create)
     {
-        if (!(dlgInfo = HeapAlloc( GetProcessHeap(), 0, sizeof(*dlgInfo) ))) return NULL;
+        if (!(dlgInfo = HeapAlloc( GetProcessHeap(), 0, sizeof(*dlgInfo) )))
+            goto out;
         dlgInfo->hwndFocus   = 0;
         dlgInfo->hUserFont   = 0;
         dlgInfo->hMenu       = 0;
@@ -348,19 +361,12 @@ DIALOGINFO *DIALOG_get_info( HWND hwnd, BOOL create )
         dlgInfo->idResult    = 0;
         dlgInfo->flags       = 0;
         dlgInfo->hDialogHeap = 0;
-        wndPtr = WIN_GetPtr( hwnd );
-        if (wndPtr && wndPtr != WND_OTHER_PROCESS && wndPtr != WND_DESKTOP)
-        {
-            wndPtr->flags |= WIN_ISDIALOG;
-            WIN_ReleasePtr( wndPtr );
-            SetWindowLongPtrW( hwnd, DWLP_WINE_DIALOGINFO, (ULONG_PTR)dlgInfo );
-        }
-        else
-        {
-            HeapFree( GetProcessHeap(), 0, dlgInfo );
-            return NULL;
-        }
+        wndPtr->dlgInfo = dlgInfo;
+        wndPtr->flags |= WIN_ISDIALOG;
     }
+
+out:
+    WIN_ReleasePtr( wndPtr );
     return dlgInfo;
 }
 
diff --git a/dlls/user32/dialog16.c b/dlls/user32/dialog16.c
index 6850d35b0d0..4fcbef41a30 100644
--- a/dlls/user32/dialog16.c
+++ b/dlls/user32/dialog16.c
@@ -434,9 +434,9 @@ static HWND DIALOG_CreateIndirect16( HINSTANCE16 hInst, LPCVOID dlgTemplate,
     }
     wndPtr = WIN_GetPtr( hwnd );
     wndPtr->flags |= WIN_ISDIALOG;
+    wndPtr->dlgInfo = dlgInfo;
     WIN_ReleasePtr( wndPtr );
 
-    SetWindowLongPtrW( hwnd, DWLP_WINE_DIALOGINFO, (LONG_PTR)dlgInfo );
     SetWindowLong16( HWND_16(hwnd), DWLP_DLGPROC, (LONG)dlgProc );
 
     if (dlgInfo->hUserFont)
diff --git a/dlls/user32/win.h b/dlls/user32/win.h
index bc024f4547f..447f4fd24d2 100644
--- a/dlls/user32/win.h
+++ b/dlls/user32/win.h
@@ -31,6 +31,7 @@
 #define WND_MAGIC     0x444e4957  /* 'WIND' */
 
 struct tagCLASS;
+struct tagDIALOGINFO;
 
 typedef struct tagWND
 {
@@ -60,6 +61,7 @@ typedef struct tagWND
     HMENU          hSysMenu;      /* window's copy of System Menu */
     HICON          hIcon;         /* window's icon */
     HICON          hIconSmall;    /* window's small icon */
+    struct tagDIALOGINFO *dlgInfo;/* Dialog additional info (dialogs only) */
     int            cbWndExtra;    /* class cbWndExtra at window creation */
     DWORD_PTR      userdata;      /* User private data */
     DWORD          wExtra[1];     /* Window extra bytes */