--- CMakeLists.txt.orig	2021-08-24 13:32:47 UTC
+++ CMakeLists.txt
@@ -34,7 +34,10 @@ if( DUNE_ENABLE_PYTHONBINDINGS )
 endif()
 
 #add sub_directories
-dune_add_subdirs(dune lib doc cmake/modules ${PYDEMO_DIR})
+dune_add_subdirs(dune lib cmake/modules ${PYDEMO_DIR})
+if (FREEBSD_INSTALL_DOCS)
+dune_add_subdirs(doc)
+endif()
 
 # finalize the dune project, e.g. generating config.h etc.
 finalize_dune_project(GENERATE_CONFIG_H_CMAKE)