--- CMakeLists.txt.orig	2022-08-06 19:21:48 UTC
+++ CMakeLists.txt
@@ -42,7 +42,7 @@ elseif(NOT CONAN_EXPORTED)
 endif()
 
 # only run documentation if this is not a sub-project
-if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+if(FREEBSD_BUILD_DOCS AND CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
     find_package(Doxygen)
     if(DOXYGEN_FOUND)
         set(DOXYGEN_OPTIMIZE_OUTPUT_FOR_C "YES")