diff --git a/INSTALL b/INSTALL
index 33f65ba5ec..13d7a17c33 100644
--- a/INSTALL
+++ b/INSTALL
@@ -197,8 +197,10 @@ BOOT_DIR=
 EFI_DIR=
 
 The make target 'rpmball' will build a xen.rpm. This variable can be
-used to append a custom string to the name.
+used to append a custom string to the name. In addition a string can be
+appended to the rpm Release: tag.
 PKG_SUFFIX=
+PKG_RELEASE=
 
 The hypervisor will report a certain version string. This variable can
 be used to append a custom string to the version.
diff --git a/tools/misc/mkrpm b/tools/misc/mkrpm
index 9b8c6d97a1..f9363a1456 100644
--- a/tools/misc/mkrpm
+++ b/tools/misc/mkrpm
@@ -17,9 +17,7 @@ xenroot="$1"
 # version and release.  Default to "0" if there isn't a release.
 v=(${2/-/ })
 version=${v[0]}
-release=${v[1]}
-
-[[ -n "$release" ]] || release="0"
+release="${v[1]:-0}${PKG_RELEASE:+.$PKG_RELEASE}"
 
 cd $xenroot