diff --git a/_constraints b/_constraints
index ac87364..f5f2f62 100644
--- a/_constraints
+++ b/_constraints
@@ -1,8 +1,24 @@
 <?xml version="1.0"?>
 <constraints>
   <hardware>
+    <disk>
+      <size unit="G">11</size>
+    </disk>
     <memory>
-      <size unit="M">6000</size>
+      <size unit="G">9</size>
     </memory>
   </hardware>
+  <overwrite>
+    <conditions>
+      <arch>x86_64</arch>
+    </conditions>
+    <hardware>
+      <disk>
+        <size unit="G">13</size>
+      </disk>
+      <memory>
+        <size unit="G">11</size>
+      </memory>
+    </hardware>
+  </overwrite>
 </constraints>
diff --git a/build20-libGL.patch b/build20-libGL.patch
deleted file mode 100644
index 47c1275..0000000
--- a/build20-libGL.patch
+++ /dev/null
@@ -1,12 +0,0 @@
-diff -ur widelands-build20/CMakeLists.txt widelands-build20_fix/CMakeLists.txt
---- widelands-build20/CMakeLists.txt	2019-05-02 07:23:39.000000000 +0200
-+++ widelands-build20_fix/CMakeLists.txt	2019-07-10 21:43:46.945029296 +0200
-@@ -181,7 +181,7 @@
- 
- # This is set to avoid linker errors when using GLVND-libs on Linux
- if("${OpenGL_GL_PREFERENCE}" STREQUAL "GLVND")
--   set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -lGL")
-+   link_libraries("GL")
-    add_compile_definitions(WL_USE_GLVND)
-    message(STATUS "Adding linker flags for GLVND.")
- endif()
diff --git a/widelands-build20.tar.bz2 b/widelands-build20.tar.bz2
deleted file mode 100644
index 2d41e75..0000000
--- a/widelands-build20.tar.bz2
+++ /dev/null
@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:38594d98c74f357d4c31dd8ee2b056bfe921f42935935af915d11b792677bcb2
-size 232364340
diff --git a/widelands-build21-source.tar.gz b/widelands-build21-source.tar.gz
new file mode 100644
index 0000000..63a3461
--- /dev/null
+++ b/widelands-build21-source.tar.gz
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:601e0e4c6f91b3fb0ece2cd1b83ecfb02344a1b9194fbb70ef3f70e06994e357
+size 381374149
diff --git a/widelands.changes b/widelands.changes
index 1a49464..428eb1f 100644
--- a/widelands.changes
+++ b/widelands.changes
@@ -1,3 +1,13 @@
+-------------------------------------------------------------------
+Sat Sep 12 09:41:42 UTC 2020 - Christophe Giboudeaux <christophe@krop.fr>
+
+- Update to build21
+  See https://www.widelands.org/changelog/ for the changelog
+- Removed obsolete conditions
+- Cleanup the %cmake call
+- Drop build20-libGL.patch. Merged upstream
+- Increase the minimum disk space required to build widelands
+
 -------------------------------------------------------------------
 Mon May  4 10:51:01 UTC 2020 - Dominique Leuenberger <dimstar@opensuse.org>
 
diff --git a/widelands.spec b/widelands.spec
index 0cf1f24..c363b40 100644
--- a/widelands.spec
+++ b/widelands.spec
@@ -17,14 +17,12 @@
 
 
 Name:           widelands
-Version:        build20
+Version:        build21
 Release:        0
 Summary:        Realtime strategy game involving map control
 License:        GPL-2.0-or-later
 URL:            https://www.widelands.org
-Source:         https://launchpad.net/%{name}/%{version}/%{version}/+download/%{name}-%{version}.tar.bz2
-# PATCH-FIX-UPSTREAM properly add -lGL as library for correct argument order
-Patch1:         build20-libGL.patch
+Source0:        https://launchpad.net/%{name}/%{version}/%{version}/+download/%{name}-%{version}-source.tar.gz
 BuildRequires:  SDL2_gfx-devel
 BuildRequires:  SDL2_image-devel
 BuildRequires:  SDL2_mixer-devel
@@ -85,41 +83,27 @@ operation.
 
 %prep
 %setup -q
-%patch1 -p1
 sed -i '/wl_add_flag(WL_COMPILE_DIAGNOSTICS "-Werror=uninitialized")/d' CMakeLists.txt
 sed -i 's/\(install(TARGETS ${NAME} DESTINATION \)"."\( COMPONENT ExecutableFiles)\)/\1bin\2/' cmake/WlFunctions.cmake
-find . -type f -name "*.py" -exec sed  -i 's/env python/python3/g' {} \;
+sed -i 's#../share#share#g' xdg/CMakeLists.txt
+find . -type f -name "*.py" -exec sed -i -E 's/env python[3]?/python3/' {} \;
 
 %build
 mkdir -p build/locale
 %define __builder ninja
 %cmake \
-  -DCMAKE_INSTALL_PREFIX=%{_prefix} \
   -DWL_INSTALL_PREFIX=%{_prefix} \
   -DWL_INSTALL_BINDIR=bin \
   -DWL_INSTALL_DATADIR=%{_datadir}/%{name} \
   -DWL_INSTALL_LOCALEDIR=%{_datadir}/%{name}/locale \
   -DCMAKE_BUILD_TYPE="Release" \
-  -DBoost_USE_STATIC_LIBS=OFF \
-  ..
+  -DBoost_USE_STATIC_LIBS=OFF
 
 %cmake_build
 
 %install
 %cmake_install
 
-for i in 16 32 48 64 128; do
-  install -D -m 0644 data/images/logos/wl-ico-${i}.png %{buildroot}%{_datadir}/icons/hicolor/${i}x${i}/apps/%{name}.png
-done
-
-install -D -m 0644 debian/org.%{name}.%{name}.desktop %{buildroot}%{_datadir}/applications/%{name}.desktop
-%suse_update_desktop_file %{name} -r Game StrategyGame
-desktop-file-edit --set-icon=%{name} %{buildroot}%{_datadir}/applications/%{name}.desktop
-
-install -D -m 0644 debian/%{name}.6 %{buildroot}%{_mandir}/man6/%{name}.6
-
-install -D -m 0644 debian/%{name}.appdata.xml %{buildroot}%{_datadir}/appdata/%{name}.appdata.xml
-
 %fdupes %{buildroot}%{_datadir}
 
 %find_lang %{name} --all-name
@@ -130,24 +114,14 @@ rm -f %{buildroot}%{_prefix}/{COPYING,CREDITS,ChangeLog,VERSION}
 # instead do post-install test
 PATH=%{buildroot}%{_bindir}:$PATH %{name} --help | grep 'This is Widelands'
 
-%if 0%{?suse_version} < 1330
-%post
-%desktop_database_post
-%icon_theme_cache_post
-
-%postun
-%desktop_database_postun
-%icon_theme_cache_postun
-%endif
-
 %files
 %license COPYING
 %doc CREDITS ChangeLog
 %{_bindir}/%{name}
-%{_datadir}/icons/hicolor/*/apps/%{name}.png
-%{_datadir}/applications/%{name}.desktop
+%{_datadir}/icons/hicolor/*/apps/org.widelands.Widelands.png
+%{_datadir}/applications/org.widelands.Widelands.desktop
 %{_mandir}/man6/%{name}.*
-%{_datadir}/appdata/%{name}.appdata.xml
+%{_datadir}/metainfo/org.widelands.Widelands.appdata.xml
 
 %files data -f %{name}.lang
 %dir %{_datadir}/%{name}