diff --git a/win/rfb_win32/ScaledDIBSectionBuffer.h b/win/rfb_win32/ScaledDIBSectionBuffer.h
index c2b8ed7..69c3848 100644
--- a/win/rfb_win32/ScaledDIBSectionBuffer.h
+++ b/win/rfb_win32/ScaledDIBSectionBuffer.h
@@ -51,6 +51,8 @@
       virtual void setScale(int scale) { setScaleRatio(double(scale)/100.0); };
       virtual void setScaleRatio(double scale_ratio);
 
+      virtual void calculateScaledBufferSize();
+
       Rect getRect() const { return ScaledPixelBuffer::getRect(); }
       Rect getRect(const Point& pos) const { return ScaledPixelBuffer::getRect(pos); }