diff --git a/uppsrc/CtrlCore/TopWin32.cpp b/uppsrc/CtrlCore/TopWin32.cpp
index ed21f534f..91a165f61 100644
--- a/uppsrc/CtrlCore/TopWin32.cpp
+++ b/uppsrc/CtrlCore/TopWin32.cpp
@@ -79,17 +79,6 @@ void TopWindow::SyncTitle()
 		::SetWindowTextW(hwnd, ToSystemCharsetW(title));
 }
 
-void TopWindow::DeleteIco()
-{
-	GuiLock __;
-	LLOG("TopWindow::DeleteIco " << UPP::Name(this));
-	if(ico)
-		DestroyIcon(ico);
-	if(lico)
-		DestroyIcon(lico);
-	ico = lico = NULL;
-}
-
 String WindowStyleAsString(dword style, dword exstyle)
 {
 	String r1;
@@ -192,14 +181,41 @@ void TopWindow::SyncCaption()
 			FlashWindowEx(&fi);
 		}
 	}
-	DeleteIco();
 
+	SetIco();
+	Ptr<TopWindow> ptr = this;
+	PostCallback([=] { // windows 11 ignores icon if Window does not start processing messages within ~200ms
+		if(ptr) ptr->SetIco(); // set it again when we are processing events
+	});
+}
+
+void TopWindow::SetIco()
+{
+	HWND hwnd = GetHWND();
 	if(hwnd) {
-		::SendMessage(hwnd, WM_SETICON, false, (LPARAM)(ico = SystemDraw::IconWin32(icon)));
-		::SendMessage(hwnd, WM_SETICON, true, (LPARAM)(lico = SystemDraw::IconWin32(largeicon)));
+		HICON new_ico = SystemDraw::IconWin32(Nvl(icon, largeicon));
+		HICON new_lico = SystemDraw::IconWin32(Nvl(largeicon, icon));
+		::SendMessage(hwnd, WM_SETICON, ICON_SMALL, (LPARAM)(new_ico));
+		::SendMessage(hwnd, WM_SETICON, ICON_BIG, (LPARAM)(new_lico));
+
+		DeleteIco();
+
+		ico = new_ico;
+		lico = new_lico;
 	}
 }
 
+void TopWindow::DeleteIco()
+{
+	GuiLock __;
+	LLOG("TopWindow::DeleteIco " << UPP::Name(this));
+	if(ico)
+		DestroyIcon(ico);
+	if(lico)
+		DestroyIcon(lico);
+	ico = lico = NULL;
+}
+
 void TopWindow::CenterRect(HWND hwnd, int center)
 {
 	GuiLock __;
diff --git a/uppsrc/CtrlCore/Win32Msg.i b/uppsrc/CtrlCore/Win32Msg.i
index 47e189694..52a1c80ca 100644
--- a/uppsrc/CtrlCore/Win32Msg.i
+++ b/uppsrc/CtrlCore/Win32Msg.i
@@ -9,6 +9,8 @@ x_MSG(WM_SETFOCUS)
 x_MSG(WM_KILLFOCUS)
 x_MSG(WM_ENABLE)
 x_MSG(WM_SETREDRAW)
+x_MSG(WM_SETICON)
+x_MSG(WM_GETICON)
 x_MSG(WM_SETTEXT)
 x_MSG(WM_GETTEXT)
 x_MSG(WM_GETTEXTLENGTH)
diff --git a/uppsrc/CtrlCore/Win32Top.h b/uppsrc/CtrlCore/Win32Top.h
index 5d2cb43da..0a430c3d6 100644
--- a/uppsrc/CtrlCore/Win32Top.h
+++ b/uppsrc/CtrlCore/Win32Top.h
@@ -7,6 +7,7 @@ private:
 	HICON       ico, lico;
 
 	void        DeleteIco();
+	void        SetIco();
 	void        CenterRect(HWND owner, int center);
 
 public:
diff --git a/upptst/TestBigIcon/main.cpp b/upptst/TestBigIcon/main.cpp
index 3b72fdd06..d64cb229b 100644
--- a/upptst/TestBigIcon/main.cpp
+++ b/upptst/TestBigIcon/main.cpp
@@ -13,6 +13,12 @@ using namespace Upp;
 GUI_APP_MAIN
 {
 	TopWindow win;
+	win.Title("TEST");
 	win.LargeIcon(TestImg::Icon());
+	DLOG("*********** OPEN MAIN");
+	win.OpenMain();
+	DLOG("*********** SLEEP 500");
+	Sleep(5000);
+	DLOG("*********** RUN");
 	win.Run();
 }