diff --git a/scripts/test_compat_api.sh b/scripts/test_compat_api.sh
index 7fb53ce2c..28b3b2053 100755
--- a/scripts/test_compat_api.sh
+++ b/scripts/test_compat_api.sh
@@ -13,7 +13,7 @@ get_old_version_branch()
     if [[ "${PARAM_OLD_VERSION_BRANCH}" != "" ]] ; then
         local BRANCH_NAME="${PARAM_OLD_VERSION_BRANCH}"
     else
-        local DEFAULT_OLD_VERSION_BRANCH="compat-api"
+        local DEFAULT_OLD_VERSION_BRANCH="compat-api-641"
         git ls-remote https://github.com/ndsev/zserio.git | \
                 grep "refs/heads/${DEFAULT_OLD_VERSION_BRANCH}" > /dev/null
         if [ $? -eq 0 ] ; then