diff --git a/include/wx/msw/private.h b/include/wx/msw/private.h
index 7e0deb8b46..982714f7bc 100644
--- a/include/wx/msw/private.h
+++ b/include/wx/msw/private.h
@@ -437,13 +437,14 @@ private:
     wxDECLARE_NO_COPY_CLASS(ScreenHDC);
 };
 
-// the same as ScreenHDC but for window DCs
+// the same as ScreenHDC but for window DCs (and if HWND is NULL, then exactly
+// the same as it)
 class WindowHDC
 {
 public:
     WindowHDC() : m_hwnd(NULL), m_hdc(NULL) { }
     WindowHDC(HWND hwnd) { m_hdc = ::GetDC(m_hwnd = hwnd); }
-   ~WindowHDC() { if ( m_hwnd && m_hdc ) { ::ReleaseDC(m_hwnd, m_hdc); } }
+   ~WindowHDC() { if ( m_hdc ) { ::ReleaseDC(m_hwnd, m_hdc); } }
 
     operator HDC() const { return m_hdc; }