--- a/configure.ac
+++ b/configure.ac
@@ -9,7 +9,8 @@ dnl  Make sure aclocal actually found it
 m4_pattern_forbid([^AX_])
 
 AC_PROG_CC
-AC_CHECK_INCLUDES_DEFAULT
+dnl not available on bullseye/buster/focal/bionic
+dnl AC_CHECK_INCLUDES_DEFAULT
 AC_PROG_EGREP
 
 AC_HEADER_TIOCGWINSZ
