diff --git a/configure.ac b/configure.ac
index d61ffc0d..0a1a5f26 100644
--- a/configure.ac
+++ b/configure.ac
@@ -131,6 +131,9 @@ AX_CXX_COMPILE_STDCXX_11([noext],[optional])
 
 XC_AUTOMAKE
 
+dnl make sure we use system extensions like _GNU_SOURCE or _XOPEN_SOURCE
+AC_USE_SYSTEM_EXTENSIONS
+
 dnl This defines _ALL_SOURCE for AIX
 CARES_CHECK_AIX_ALL_SOURCE
 
@@ -138,9 +141,6 @@ dnl Our configure and build reentrant settings
 CARES_CONFIGURE_THREAD_SAFE
 CARES_CONFIGURE_REENTRANT
 
-dnl make sure we use system extensions like _GNU_SOURCE or _XOPEN_SOURCE
-AC_USE_SYSTEM_EXTENSIONS
-
 dnl check for how to do large files
 AC_SYS_LARGEFILE