diff --git a/llvm/utils/release/tag.sh b/llvm/utils/release/tag.sh
index 2dfba04..503413b 100755
--- a/llvm/utils/release/tag.sh
+++ b/llvm/utils/release/tag.sh
@@ -117,7 +117,7 @@
 if [ "x$rc" = "x" ]; then
     tag_version
 else
-    if [ "x$revision" != "x" ]; then
+    if [ "$revision" != "HEAD" ]; then
         echo "error: cannot use -revision with -rc"
         echo
         usage