diff -up siril-0.99.6/configure.ac.opencv_flann siril-0.99.6/configure.ac
--- siril-0.99.6/configure.ac.opencv_flann 2020-09-22 22:01:48.000000000 +0200
+++ siril-0.99.6/configure.ac 2020-10-21 10:27:10.271118853 +0200
@@ -160,7 +160,7 @@ if test -n "$CXX" && ( test "X$CXX" != "
dnl http://nerdland.net/2009/07/detecting-c-libraries-with-autotools/ solution 2
dnl we handle 2 opencv versions because of a debian bug with opencv2 and GTK3
PKG_CHECK_MODULES([OPENCV], [opencv >= 3.0],
- [OPENCV_LIBS="-lopencv_core -lopencv_imgproc -lopencv_calib3d"],
+ [OPENCV_LIBS="-lopencv_core -lopencv_imgproc -lopencv_calib3d -lopencv_flann"],
[PKG_CHECK_MODULES([OPENCV], [opencv >= 2.0],
[OPENCV_LIBS="-lopencv_core -lopencv_imgproc"],
[PKG_CHECK_MODULES([OPENCV], [opencv4],