diff --git a/src/gui/dialog.c b/src/gui/dialog.c
index d12b906a..8c04141f 100644
--- a/src/gui/dialog.c
+++ b/src/gui/dialog.c
@@ -183,9 +183,12 @@ int GUIAPI DialogBoxIndirectParamEx (PDLGTEMPLATE pDlgTemplate,
     int  retCode = IDCANCEL;
     MSG Msg;
 
-    if(hOwner && hOwner != HWND_INVALID && hOwner != HWND_DESKTOP)
+    if (hOwner && hOwner != HWND_INVALID && hOwner != HWND_DESKTOP)
         hOwner = GetMainWindowHandle(hOwner);
 
+    /* Since 5.0.0: use internal extended style for dialgbox */
+    pDlgTemplate->dwExStyle |= WS_EX_DIALOGBOX;
+
     hDlg = CreateMainWindowIndirectParamEx(pDlgTemplate,
         hOwner, DlgProc, lParam,
         werdr_name, we_attrs,
@@ -194,9 +197,6 @@ int GUIAPI DialogBoxIndirectParamEx (PDLGTEMPLATE pDlgTemplate,
     if (hDlg == HWND_INVALID)
         return -1;
 
-    /* Since 5.0.0: use internal extended style for dialgbox */
-    IncludeWindowExStyle (hDlg, WS_EX_DIALOGBOX);
-
     //MiniGUI maybe change dialog owner in CreateMainWindow, so we
     //should update its owner by GetHosting.
     hOwner = GetHosting (hDlg);