diff --git a/cf/aix.m4 b/cf/aix.m4
index c20555f3a..5d0be4f14 100644
--- a/cf/aix.m4
+++ b/cf/aix.m4
@@ -15,7 +15,7 @@ case "$host" in
 esac
 
 AM_CONDITIONAL(AIX, test "$aix" != no)dnl
-AM_CONDITIONAL(AIX4, test "$aix" = 4)
+AM_CONDITIONAL(AIX4, test "$aix" = 4)dnl
 
 
 AC_ARG_ENABLE(dynamic-afs,
@@ -45,8 +45,11 @@ fi
 AM_CONDITIONAL(AIX_DYNAMIC_AFS, test "$enable_dynamic_afs" != no)dnl
 AC_SUBST(AIX_EXTRA_KAFS)dnl
 
+if test "$aix" != no; then
+	AC_DEFINE([_ALL_SOURCE],1,[Required for functional/sane headers on AIX])
+fi
+
 AH_BOTTOM([#if _AIX
-#define _ALL_SOURCE
 /* XXX this is gross, but kills about a gazillion warnings */
 struct ether_addr;
 struct sockaddr;
diff --git a/configure.in b/configure.in
index 1269e6a2a..b8ebc0241 100644
--- a/configure.in
+++ b/configure.in
@@ -29,6 +29,10 @@ AB_INIT
 
 rk_SYS_LARGEFILE
 
+rk_AIX
+rk_IRIX
+rk_SUNOS
+
 dnl
 dnl this is needed to run the configure tests against glibc
 dnl
@@ -215,10 +219,6 @@ rk_TEST_PACKAGE(hesiod,[#include <hesiod.h>],-lhesiod,,, HESIOD)
 KRB_C_BIGENDIAN
 AC_C_INLINE
 
-rk_AIX
-rk_IRIX
-rk_SUNOS
-
 KRB_CHECK_X
 
 AM_CONDITIONAL(HAVE_X, test "$no_x" != yes)