diff --git a/uppsrc/CtrlCore/TopWin32.cpp b/uppsrc/CtrlCore/TopWin32.cpp
index f02cdbf73..490a8bb1d 100644
--- a/uppsrc/CtrlCore/TopWin32.cpp
+++ b/uppsrc/CtrlCore/TopWin32.cpp
@@ -164,7 +164,7 @@ void TopWindow::SyncCaption()
 	style |= WS_CAPTION;
 	if(hasdhctrl)
 		style |= WS_CLIPSIBLINGS|WS_CLIPCHILDREN;
-	if(minimizebox)
+	if(minimizebox && !GetOwner())
 		style |= WS_MINIMIZEBOX;
 	if(maximizebox)
 		style |= WS_MAXIMIZEBOX;