*** pth.h.in.ORIG	Tue Oct  9 12:55:13 2007
--- pth.h.in	Tue Oct  9 12:55:57 2007
***************
*** 90,96 ****
--- 90,100 ----
      /* check if the user requests a bigger FD_SETSIZE than we can handle */
  #if defined(FD_SETSIZE)
  #if FD_SETSIZE > @PTH_FDSETSIZE@
+ #ifdef _AIX
+ #define FD_SETSIZE 65534
+ #else
  #error "FD_SETSIZE is larger than what GNU Pth can handle."
+ #endif
  #endif
  #endif
  
--- aclocal.m4.ORIGIN	2017-11-09 10:31:17 +0100
+++ aclocal.m4	2017-11-09 10:33:13 +0100
@@ -1214,8 +1214,8 @@
 AC_ARG_WITH(fdsetsize,dnl
 [  --with-fdsetsize=NUM    set FD_SETSIZE while building GNU Pth],[
 case $withval in
-    [[1-9]][[0-9]]|[[1-9]][[0-9]][[0-9]]|[[1-9]][[0-9]][[0-9]][[0-9]]) $1=$withval ;;
-    * ) AC_ERROR([invalid FD_SETSIZE specified -- allowed: 10-9999]) ;;
+    [[1-9]][[0-9]]|[[1-9]][[0-9]][[0-9]]|[[1-9]][[0-9]][[0-9]][[0-9]]|[[1-9]][[0-9]][[0-9]][[0-9]][[0-9]]) $1=$withval ;;
+    * ) AC_ERROR([invalid FD_SETSIZE specified -- allowed: 10-99999]) ;;
 esac
 dnl # we cannot use the usual
 dnl # AC_DEFINE_UNQUOTED(FD_SETSIZE, $$1, [Define to the maximum size of fd_set])
--- configure.ORIGIN	2017-11-09 10:40:38 +0100
+++ configure	2017-11-09 10:41:22 +0100
@@ -19667,9 +19667,9 @@
   withval="$with_fdsetsize"
 
 case $withval in
-    [1-9][0-9]|[1-9][0-9][0-9]|[1-9][0-9][0-9][0-9]) PTH_FDSETSIZE=$withval ;;
-    * ) { { echo "$as_me:$LINENO: error: invalid FD_SETSIZE specified -- allowed: 10-9999" >&5
-echo "$as_me: error: invalid FD_SETSIZE specified -- allowed: 10-9999" >&2;}
+    [1-9][0-9]|[1-9][0-9][0-9]|[1-9][0-9][0-9][0-9]|[1-9][0-9][0-9][0-9][0-9]) PTH_FDSETSIZE=$withval ;;
+    * ) { { echo "$as_me:$LINENO: error: invalid FD_SETSIZE specified -- allowed: 10-99999" >&5
+echo "$as_me: error: invalid FD_SETSIZE specified -- allowed: 10-99999" >&2;}
    { (exit 1); exit 1; }; } ;;
 esac
 CPPFLAGS="$CPPFLAGS -DFD_SETSIZE=$PTH_FDSETSIZE"