diff -up Linux-PAM-1.0.4/configure.in.autoreconf Linux-PAM-1.0.4/configure.in
--- Linux-PAM-1.0.4/configure.in.autoreconf	2009-03-16 16:57:54.000000000 +0100
+++ Linux-PAM-1.0.4/configure.in	2009-03-16 16:57:54.000000000 +0100
@@ -72,7 +72,7 @@ fi
 AM_CONDITIONAL([STATIC_MODULES], [test "$STATIC_MODULES" != "no"])
 
 dnl Checks for programs.
-AC_GNU_SOURCE
+AC_USE_SYSTEM_EXTENSIONS
 AC_PROG_CC
 AC_PROG_YACC
 AM_PROG_LEX