--- gtkmm-4.16.0.old/meson.build
+++ gtkmm-4.16.0/meson.build
@@ -180,9 +180,9 @@
   mm_common_get = find_program('mm-common-get', required: true)
 endif
 m4 = find_program('m4', required: maintainer_mode) # Used by gmmproc (in glibmm)
-doxygen = find_program('doxygen', required: build_documentation)
-dot = find_program('dot', required: build_documentation) # Used by Doxygen
-xsltproc = find_program('xsltproc', required: build_documentation)
+doxygen = find_program('doxygen', required: false)
+dot = find_program('dot', required: false) # Used by Doxygen
+xsltproc = find_program('xsltproc', required: false)
 
 # Script files copied to 'untracked' by mm-common-get.
 script_dir = project_source_root / 'untracked' / 'build_scripts'