diff --git a/tools/update-swift-syntax.sh b/tools/update-swift-syntax.sh
index a9fc624ea2..9a452b538d 100755
--- a/tools/update-swift-syntax.sh
+++ b/tools/update-swift-syntax.sh
@@ -2,7 +2,7 @@
 
 set -euo pipefail
 
-readonly old_commit="$(grep "apple/swift-syntax" Package.swift | sed -nr 's/.*revision: \"([a-f0-9]{40})\"),$/\1/p')"
+readonly old_commit="$(grep "apple/swift-syntax" Package.swift | sed -nr 's/.*revision: \"([a-f0-9]{40})\"\),$/\1/p')"
 if [ $# -eq 0 ]; then
   readonly new_commit="$(curl -s -H "Authorization: token $GITHUB_TOKEN" -H "Accept: application/vnd.github.VERSION.sha" "https://api.github.com/repos/apple/swift-syntax/commits/main")"
 else