--- a/src/extension/internal/Makefile_insert.orig	2019-11-10 11:29:46.165916037 +0100
+++ b/src/extension/internal/Makefile_insert	2019-11-10 11:30:04.644916726 +0100
@@ -68,8 +68,6 @@
 	extension/internal/bitmap/normalize.h			\
 	extension/internal/bitmap/oilPaint.cpp			\
 	extension/internal/bitmap/oilPaint.h			\
-	extension/internal/bitmap/opacity.cpp			\
-	extension/internal/bitmap/opacity.h			\
 	extension/internal/bitmap/raise.cpp			\
 	extension/internal/bitmap/raise.h			\
 	extension/internal/bitmap/reduceNoise.cpp		\