--- CMakeLists.txt.orig	2020-03-14 18:22:22 UTC
+++ CMakeLists.txt
@@ -25,7 +25,9 @@ dune_project()
 
 add_subdirectory(cmake/modules)
 add_subdirectory(dune)
+if (FREEBSD_INSTALL_DOCS)
 add_subdirectory(doc)
+endif()
 add_subdirectory(lib)
 
 # finalize the dune project, e.g. generating config.h etc.