diff -up mpir-1.3.1/configure.in.s390x mpir-1.3.1/configure.in
--- mpir-1.3.1/configure.in.s390x	2010-01-30 23:13:19.000000000 +0100
+++ mpir-1.3.1/configure.in	2011-06-16 10:24:58.000000000 +0200
@@ -1059,6 +1059,11 @@ case $host in
     ;;
 
 
+  s390x-*-*)
+    gcc_cflags="-O2 $fomit_frame_pointer"
+    path="s390x"
+    #extra_functions="udiv_w_sdiv"
+    ;;
   # IBM s/370 and similar
   [s3[6-9]0*-*-*])
     gcc_cflags="-O2 $fomit_frame_pointer"
diff -up mpir-1.3.1/configure.s390x mpir-1.3.1/configure
--- mpir-1.3.1/configure.s390x	2011-06-16 10:22:58.000000000 +0200
+++ mpir-1.3.1/configure	2011-06-16 10:24:38.000000000 +0200
@@ -3749,6 +3749,11 @@ _ACEOF
     ;;
 
 
+  s390x-*-*)
+    gcc_cflags="-O2 $fomit_frame_pointer"
+    path="s390x"
+    #extra_functions="udiv_w_sdiv"
+    ;;
   # IBM s/370 and similar
   s3[6-9]0*-*-*)
     gcc_cflags="-O2 $fomit_frame_pointer"
diff -up mpir-1.3.1/mpn/s390/gmp-mparam.h.s390x mpir-1.3.1/mpn/s390/gmp-mparam.h
--- mpir-1.3.1/mpn/s390/gmp-mparam.h.s390x	2010-01-30 23:12:42.000000000 +0100
+++ mpir-1.3.1/mpn/s390/gmp-mparam.h	2011-06-16 10:22:21.000000000 +0200
@@ -20,7 +20,8 @@ the Free Software Foundation, Inc., 51 F
 MA 02110-1301, USA. */
 
 
-/* BITS_PER_MP_LIMB etc generated by configure */
+#define BITS_PER_MP_LIMB 32
+#define BYTES_PER_MP_LIMB 4
 
 
 /* Generated by tuneup.c, 2001-12-03, gcc 2.95 */
diff -up mpir-1.3.1/mpn/s390x/gmp-mparam.h.s390x mpir-1.3.1/mpn/s390x/gmp-mparam.h
--- mpir-1.3.1/mpn/s390x/gmp-mparam.h.s390x	2011-06-16 10:22:21.000000000 +0200
+++ mpir-1.3.1/mpn/s390x/gmp-mparam.h	2011-06-16 10:22:21.000000000 +0200
@@ -0,0 +1,27 @@
+/* gmp-mparam.h -- Compiler/machine parameter header file.
+
+Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Library General Public License as published by
+the Free Software Foundation; either version 2 of the License, or (at your
+option) any later version.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
+License for more details.
+
+You should have received a copy of the GNU Library General Public License
+along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#define BITS_PER_MP_LIMB 64
+#define BYTES_PER_MP_LIMB 8
+#define BITS_PER_LONGINT 64
+#define BITS_PER_INT 32
+#define BITS_PER_SHORTINT 16
+#define BITS_PER_CHAR 8