diff --git a/make_release b/make_release
index d569ea7..4ecb8fa 100755
--- a/make_release
+++ b/make_release
@@ -2,9 +2,13 @@
 
 proj="iperf"
 
+if [ "x$2" != "x" ]; then
+tag=$2
+else
 tag=`awk '/IPERF_VERSION / {
   gsub(/"/, "", $3);
   print $3 }' src/version.h`
+fi
 
 dirname=`echo $tag $proj | awk '{
   gsub(/-ALPHA/, "a", $1);
@@ -12,8 +16,8 @@ dirname=`echo $tag $proj | awk '{
   gsub(/-RELEASE/, "", $1);
   print $2"-"$1 }'`
 
-echo tag $tag
-echo dirname $dirname
+# echo tag $tag
+# echo dirname $dirname
 
 do_tag ()
 {
@@ -23,7 +27,17 @@ do_tag ()
 do_tar ()
 {
     tarball=${dirname}.tar.gz
-    hg archive -t tgz -p ${dirname} -X make_release -X .hgtags -r ${tag} ${tarball}
+    rm -f ${tarball}
+    hg archive -t tgz -p ${dirname} -X .hg\* -r ${tag} ${tarball}
+
+    # Compute SHA256 hash
+    case `uname -s` in
+	FreeBSD) sha=sha256 ;;
+	Linux) sha=sha256sum ;;
+	Darwin) sha="shasum -a 256" ;;
+	*) sha=echo ;;
+    esac
+    ${sha} ${tarball}
 }
 
 usage ()
@@ -31,13 +45,18 @@ usage ()
     cat <<EOF
 $0: tag|tar
 
-   tag  -- create a tag using the contents of src/version.h
-   tar  -- create a tarball of the current tag
+   tag  -- create a tag
+   tar  -- create a tarball from a tag
 
 General use is to do:
 
 ./$0 tag
 ./$0 tar
+
+An optional argument may be specified to both the tag and tar
+subcommands to explicitly specify a tag string.  If not specified, the
+contents of src/version.h are used.
+
 EOF
 }