diff --git a/reactos/subsys/win32k/dib/dib.h b/reactos/subsys/win32k/dib/dib.h
index 37f3887df8a..2c989a9f79d 100644
--- a/reactos/subsys/win32k/dib/dib.h
+++ b/reactos/subsys/win32k/dib/dib.h
@@ -120,7 +120,7 @@ BOOLEAN DIB_32BPP_BitBltSrcCopy(PBLTINFO);
 BOOLEAN DIB_32BPP_StretchBlt(SURFOBJ*,SURFOBJ*,RECTL*,RECTL*,POINTL*,POINTL,CLIPOBJ*,XLATEOBJ*,ULONG);
 BOOLEAN DIB_32BPP_TransparentBlt(SURFOBJ*,SURFOBJ*,RECTL*,POINTL*,XLATEOBJ*,ULONG);
 
-BOOLEAN DIB_32DstInvert(PBLTINFO);
+VOID FASTCALL DIB_32DstInvert(PBLTINFO BltInfo);
 BOOLEAN DIB32_Srccopy(PBLTINFO BltInfo);
 BOOLEAN DIB32_ColorFill(PBLTINFO BltInfo, ULONG);
 BOOLEAN DIB32_SrcPaint(PBLTINFO BltInfo);