diff --git a/decimal.patch b/decimal.patch
new file mode 100644
index 0000000..dc69770
--- /dev/null
+++ b/decimal.patch
@@ -0,0 +1,33 @@
+diff -ur a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
+--- a/Modules/_decimal/_decimal.c	2021-02-19 13:31:44.000000000 +0100
++++ b/Modules/_decimal/_decimal.c	2021-02-21 10:25:28.240876775 +0100
+@@ -3280,7 +3280,7 @@
+     }
+     else {
+         size_t n = strlen(spec.dot);
+-        if (n > 1 || (n == 1 && !isascii((uchar)spec.dot[0]))) {
++        if (n > 1 || (n == 1 && !isascii((unsigned char)spec.dot[0]))) {
+             /* fix locale dependent non-ascii characters */
+             dot = dotsep_as_utf8(spec.dot);
+             if (dot == NULL) {
+@@ -3289,7 +3289,7 @@
+             spec.dot = PyBytes_AS_STRING(dot);
+         }
+         n = strlen(spec.sep);
+-        if (n > 1 || (n == 1 && !isascii((uchar)spec.sep[0]))) {
++        if (n > 1 || (n == 1 && !isascii((unsigned char)spec.sep[0]))) {
+             /* fix locale dependent non-ascii characters */
+             sep = dotsep_as_utf8(spec.sep);
+             if (sep == NULL) {
+diff -ur a/setup.py b/setup.py
+--- a/setup.py	2021-02-19 13:31:44.000000000 +0100
++++ b/setup.py	2021-02-21 10:25:28.240876775 +0100
+@@ -2196,7 +2196,7 @@
+         undef_macros = []
+         if '--with-system-libmpdec' in sysconfig.get_config_var("CONFIG_ARGS"):
+             include_dirs = []
+-            libraries = [':libmpdec.so.2']
++            libraries = ['mpdec']
+             sources = ['_decimal/_decimal.c']
+             depends = ['_decimal/docstrings.h']
+         else:
diff --git a/python39.changes b/python39.changes
index d7928c7..c8f7856 100644
--- a/python39.changes
+++ b/python39.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Fri Aug 27 12:00:12 UTC 2021 - Matej Cepl <mcepl@suse.com>
+
+- Add decimal.patch to add building with --with-system-libmpdec
+  option (bsc#1189356).
+
 -------------------------------------------------------------------
 Thu Aug 26 11:25:12 UTC 2021 - Andreas Schwab <schwab@suse.de>
 
diff --git a/python39.spec b/python39.spec
index 0e68ede..f7c9451 100644
--- a/python39.spec
+++ b/python39.spec
@@ -76,6 +76,12 @@
 %if "%{_arch}" == "arm"
 %define armsuffix hf
 %endif
+# Decide whether we want to use mpdecimal
+%if 0%{?suse_version} >= 1550
+%bcond_without mpdecimal
+%else
+%bcond_with mpdecimal
+%endif
 # pyexpat.cpython-35m-x86_64-linux-gnu
 # pyexpat.cpython-35m-powerpc64le-linux-gnu
 # pyexpat.cpython-35m-armv7-linux-gnueabihf
@@ -120,6 +126,10 @@ Patch02:        F00251-change-user-install-location.patch
 # PATCH-FEATURE-UPSTREAM distutils-reproducible-compile.patch gh#python/cpython#8057 mcepl@suse.com
 # Improve reproduceability
 Patch06:        distutils-reproducible-compile.patch
+# PATCH-FEATURE-UPSTREAM decimal.patch bsc#1189356 mcepl@suse.com
+# fix building with mpdecimal
+# https://www.bytereef.org/contrib/decimal.diff
+Patch05:        decimal.patch
 # support finding packages in /usr/local, install to /usr/local by default
 Patch07:        python-3.3.0b1-localpath.patch
 # replace DATE, TIME and COMPILER by fixed definitions to aid reproducible builds
@@ -159,6 +169,9 @@ BuildRequires:  pkgconfig(zlib)
 BuildRequires:  pkgconfig(libnsl)
 BuildRequires:  pkgconfig(libtirpc)
 %endif
+%if %{with mpdecimal}
+BuildRequires:  mpdecimal-devel
+%endif
 %if %{with doc}
 %if 0%{?suse_version} >= 1550
 BuildRequires:  %{python_pkg_name}-Sphinx
@@ -389,6 +402,9 @@ other applications.
 %if 0%{?sle_version} && 0%{?sle_version} <= 150300
 %patch34 -p1
 %endif
+%if %{with mpdecimal}
+%patch05 -p1
+%endif
 
 # drop Autoconf version requirement
 sed -i 's/^AC_PREREQ/dnl AC_PREREQ/' configure.ac
@@ -450,6 +466,9 @@ export CFLAGS="%{optflags} -IVendor/"
     --with-lto \
 %if %{with profileopt}
     --enable-optimizations \
+%endif
+%if %{with mpdecimal}
+    --with-system-libmpdec \
 %endif
     --enable-loadable-sqlite-extensions