--- configure.ac.orig	2023-03-03 20:18:56 UTC
+++ configure.ac
@@ -83,6 +83,8 @@ AC_SUBST(FLTK_CFLAGS,"$(fltk-config --use-gl --use-ima
 AS_CASE([${host_os}],
 	[darwin*],
 	[AC_SUBST(FLTK_LIBS,"$(fltk-config --use-gl --use-images --ldflags)")],
+	[freebsd*],
+	[AC_SUBST(FLTK_LIBS,"-lGL $(fltk-config --use-gl --use-images --ldflags)")],
 	[linux*],
 	[AC_SUBST(FLTK_LIBS,"-lGL $(fltk-config --use-gl --use-images --ldflags)")]
 )