diff --git a/gmp.changes b/gmp.changes
index 04fad1b..7fc67db 100644
--- a/gmp.changes
+++ b/gmp.changes
@@ -1,3 +1,17 @@
+-------------------------------------------------------------------
+Wed Mar 19 17:33:11 UTC 2025 - Richard Biener <rguenther@suse.com>
+
+- Use -std=gnu17 for SLE16 and higher to aovid C23 conformance issues
+  with GCC 15. 
+
+-------------------------------------------------------------------
+Thu Feb 27 08:25:36 UTC 2025 - Richard Biener <rguenther@suse.com>
+
+- Manually select the z13/z14 architecture level specific assembly routines
+  for s390x and SLFO since GMP lacks fat binary support there and also lacks
+  a way to auto-detect the architecture level used at compile-time.
+  [jsc#PED-3270]
+
 -------------------------------------------------------------------
 Tue Feb 27 11:03:46 UTC 2024 - Dominique Leuenberger <dimstar@opensuse.org>
 
diff --git a/gmp.spec b/gmp.spec
index aa4e51d..f9fcbef 100644
--- a/gmp.spec
+++ b/gmp.spec
@@ -1,7 +1,7 @@
 #
 # spec file for package gmp
 #
-# Copyright (c) 2023 SUSE LLC
+# Copyright (c) 2025 SUSE LLC
 #
 # All modifications and additions to the file contributed by third parties
 # remain the property of their copyright owners, unless otherwise agreed
@@ -70,7 +70,7 @@ Group:          Development/Languages/C and C++
 Requires:       libgmp10 = %{version}
 Requires:       libgmpxx4 = %{version}
 Requires(pre):  %{install_info_prereq}
-Requires(preun):%{install_info_prereq}
+Requires(preun): %{install_info_prereq}
 
 %description devel
 These libraries are needed to develop programs which calculate with
@@ -82,7 +82,19 @@ huge numbers (integer and floating point).
 %patch -P 2 -p1
 
 %build
+# s390x lacks fat binary support and the gmp configury does not figure
+# the architecture level enabled by the compiler.  For SLFO make it
+# use the z13/z14 architecture specific routines.
+%ifarch s390x
+%if 0%{?suse_version} >= 1600 && !0%{?is_opensuse}
+export MPN_PATH="s390_64/z14 s390_64/z13 s390_64 generic"
+%endif
+%endif
+%if %{suse_version} >= 1600
+export CFLAGS="%{optflags} -fexceptions -std=gnu17"
+%else
 export CFLAGS="%{optflags} -fexceptions"
+%endif
 %configure \
   --disable-static \
   --enable-cxx \