diff --git a/src/msw/nonownedwnd.cpp b/src/msw/nonownedwnd.cpp
index 88d302b235..19b489394e 100644
--- a/src/msw/nonownedwnd.cpp
+++ b/src/msw/nonownedwnd.cpp
@@ -318,7 +318,7 @@ bool wxNonOwnedWindow::HandleDPIChange(const wxSize& newDPI, const wxRect& newRe
         wxRect actualNewRect = newRect;
         if ( wxSizer* sizer = GetSizer() )
         {
-            const wxSize minSize = ClientToWindowSize(sizer->GetMinSize());
+            const wxSize minSize = sizer->ComputeFittingClientSize(this);
             wxSize diff = minSize - newRect.GetSize();
 
             // We don't want to shrink the window as if the user had increased