diff --git a/include/gdiplusflat.h b/include/gdiplusflat.h
index 78db330..d308c2a 100644
--- a/include/gdiplusflat.h
+++ b/include/gdiplusflat.h
@@ -29,6 +29,7 @@
 
 GpStatus WINGDIPAPI GdipCreatePen1(ARGB,REAL,GpUnit,GpPen**);
 GpStatus WINGDIPAPI GdipDeletePen(GpPen*);
+GpStatus WINGDIPAPI GdipSetPenEndCap(GpPen*,GpLineCap);
 
 GpStatus WINGDIPAPI GdipCreateFromHDC(HDC,GpGraphics**);
 GpStatus WINGDIPAPI GdipCreateFromHWND(HWND,GpGraphics**);