--- CMakeLists.txt.orig	2020-03-14 17:27:33 UTC
+++ CMakeLists.txt
@@ -21,7 +21,9 @@ include(DuneMacros)
 dune_project()
 
 add_subdirectory("dune")
+if (FREEBSD_INSTALL_DOCS)
 add_subdirectory("doc")
+endif()
 add_subdirectory("lib")
 
 # finalize the dune project, e.g. generating config.h etc.
