diff --git a/ci-image/scripts/ga-typecheck.sh b/ci-image/scripts/ga-typecheck.sh
index e4b792c..3064a68 100755
--- a/ci-image/scripts/ga-typecheck.sh
+++ b/ci-image/scripts/ga-typecheck.sh
@@ -10,7 +10,7 @@ source virtualenv/bin/activate
 pip install pyright
 
 cd src/${GITHUB_REPOSITORY##*/}
-HEAD_REV="$(git rev-parse --abbrev-ref HEAD)"
+HEAD_REV="$(git rev-parse HEAD)"
 if [[ $GITHUB_REF == "master" ]]; then
     BASE_REV="$(git rev-parse --abbrev-ref HEAD~)"
 else