diff --git a/configure.in b/configure.in
index a8448ec..2076f32 100644
--- a/configure.in
+++ b/configure.in
@@ -595,7 +595,7 @@
 
 
 # checks for UNIX variants that set C preprocessor variables
-AC_AIX
+AC_USE_SYSTEM_EXTENSIONS
 
 # Check for unsupported systems
 case $ac_sys_system/$ac_sys_release in