diff --git a/configure.ac b/configure.ac
index cfaaa7d85..0066dbfbb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -14,9 +14,7 @@ AM_MAINTAINER_MODE
 
 AC_CANONICAL_HOST
 
-AC_GNU_SOURCE
-AC_AIX
-AC_MINIX
+AC_USE_SYSTEM_EXTENSIONS
 AC_ISC_POSIX
 
 AC_PROG_CC_STDC