diff --git a/_service b/_service
index 103f106..231be7e 100644
--- a/_service
+++ b/_service
@@ -11,4 +11,8 @@
   <service name="set_version" mode="disabled" />
 
   <service name="tar" mode="buildtime"/>
+  <service name="recompress" mode="buildtime">
+    <param name="file">*.tar</param>
+    <param name="compression">xz</param>
+  </service>
 </services>
diff --git a/b4.spec b/b4.spec
index 1bee940..711d5a5 100644
--- a/b4.spec
+++ b/b4.spec
@@ -25,7 +25,7 @@ Summary:        Helper scripts for kernel.org patches
 License:        GPL-2.0-or-later
 Group:          Development/Tools/Other
 URL:            https://git.kernel.org/pub/scm/utils/b4/b4.git
-Source0:        %{name}-%{version}.tar
+Source0:        %{name}-%{version}.tar.xz
 BuildArch:      noarch
 BuildRequires:  %{python_module setuptools}
 BuildRequires:  tar