diff --git a/dlls/user32/button.c b/dlls/user32/button.c
index 42163eb3124..6e68785342f 100644
--- a/dlls/user32/button.c
+++ b/dlls/user32/button.c
@@ -113,8 +113,6 @@ static void GB_Paint( HWND hwnd, HDC hDC, UINT action );
 static void UB_Paint( HWND hwnd, HDC hDC, UINT action );
 static void OB_Paint( HWND hwnd, HDC hDC, UINT action );
 static void BUTTON_CheckAutoRadioButton( HWND hwnd );
-static LRESULT WINAPI ButtonWndProcA( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam );
-static LRESULT WINAPI ButtonWndProcW( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam );
 
 #define MAX_BTN_TYPE  12
 
@@ -164,8 +162,8 @@ const struct builtin_class_descr BUTTON_builtin_class =
 {
     buttonW,             /* name */
     CS_DBLCLKS | CS_VREDRAW | CS_HREDRAW | CS_PARENTDC, /* style  */
-    ButtonWndProcA,      /* procA */
-    ButtonWndProcW,      /* procW */
+    NULL,                /* procA */
+    BUILTIN_WINPROC(WINPROC_BUTTON),  /* procW */
     NB_EXTRA_BYTES,      /* extra */
     IDC_ARROW,           /* cursor */
     0                    /* brush */
@@ -238,6 +236,8 @@ LRESULT ButtonWndProc_common(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam,
     LONG state;
     HANDLE oldHbitmap;
 
+    if (!IsWindow( hWnd )) return 0;
+
     pt.x = (short)LOWORD(lParam);
     pt.y = (short)HIWORD(lParam);
 
@@ -545,26 +545,6 @@ LRESULT ButtonWndProc_common(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam,
     return 0;
 }
 
-/***********************************************************************
- *           ButtonWndProcW
- */
-static LRESULT WINAPI ButtonWndProcW( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
-{
-    if (!IsWindow( hWnd )) return 0;
-    return wow_handlers.button_proc( hWnd, uMsg, wParam, lParam, TRUE );
-}
-
-
-/***********************************************************************
- *           ButtonWndProcA
- */
-static LRESULT WINAPI ButtonWndProcA( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
-{
-    if (!IsWindow( hWnd )) return 0;
-    return wow_handlers.button_proc( hWnd, uMsg, wParam, lParam, FALSE );
-}
-
-
 /**********************************************************************
  * Convert button styles to flags used by DrawText.
  */
diff --git a/dlls/user32/controls.h b/dlls/user32/controls.h
index 45dd2d0824e..501520f086c 100644
--- a/dlls/user32/controls.h
+++ b/dlls/user32/controls.h
@@ -31,6 +31,15 @@
 #define WINSWITCH_CLASS_ATOM MAKEINTATOM(32771)  /* WinSwitch */
 #define ICONTITLE_CLASS_ATOM MAKEINTATOM(32772)  /* IconTitle */
 
+enum builtin_winprocs
+{
+    WINPROC_BUTTON = 0,
+    NB_BUILTIN_WINPROCS
+};
+
+#define WINPROC_HANDLE (~0u >> 16)
+#define BUILTIN_WINPROC(index) ((WNDPROC)(ULONG_PTR)((index) | (WINPROC_HANDLE << 16)))
+
 /* Built-in class descriptor */
 struct builtin_class_descr
 {
diff --git a/dlls/user32/winproc.c b/dlls/user32/winproc.c
index 0bde5309798..dd3e2346279 100644
--- a/dlls/user32/winproc.c
+++ b/dlls/user32/winproc.c
@@ -44,7 +44,6 @@ typedef struct tagWINDOWPROC
     WNDPROC        procW;    /* Unicode window proc */
 } WINDOWPROC;
 
-#define WINPROC_HANDLE (~0u >> 16)
 #define MAX_WINPROCS  4096
 #define BUILTIN_WINPROCS 9  /* first BUILTIN_WINPROCS entries are reserved for builtin procs */
 #define MAX_WINPROC_RECURSION  64
@@ -52,8 +51,15 @@ typedef struct tagWINDOWPROC
 
 WNDPROC EDIT_winproc_handle = 0;
 
-static WINDOWPROC winproc_array[MAX_WINPROCS];
-static UINT builtin_used;
+static LRESULT WINAPI ButtonWndProcA( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam );
+static LRESULT WINAPI ButtonWndProcW( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam );
+
+static WINDOWPROC winproc_array[MAX_WINPROCS] =
+{
+    { ButtonWndProcA, ButtonWndProcW },  /* WINPROC_BUTTON */
+};
+
+static UINT builtin_used = NB_BUILTIN_WINPROCS;
 static UINT winproc_used = BUILTIN_WINPROCS;
 
 static CRITICAL_SECTION winproc_cs;
@@ -1032,6 +1038,21 @@ INT_PTR WINPROC_CallDlgProcW( DLGPROC func, HWND hwnd, UINT msg, WPARAM wParam,
 }
 
 
+/***********************************************************************
+ * Window procedures for builtin classes
+ */
+
+static LRESULT WINAPI ButtonWndProcA( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam )
+{
+    return wow_handlers.button_proc( hwnd, msg, wParam, lParam, FALSE );
+}
+
+static LRESULT WINAPI ButtonWndProcW( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam )
+{
+    return wow_handlers.button_proc( hwnd, msg, wParam, lParam, TRUE );
+}
+
+
 /**********************************************************************
  *		UserRegisterWowHandlers (USER32.@)
  *