diff --git a/ct/semaphore.sh b/ct/semaphore.sh
index 6013a8edf..e3825a9a6 100644
--- a/ct/semaphore.sh
+++ b/ct/semaphore.sh
@@ -10,7 +10,7 @@ var_tags="${var_tags:-dev_ops}"
 var_cpu="${var_cpu:-2}"
 var_ram="${var_ram:-2048}"
 var_disk="${var_disk:-4}"
-var_os="${var_os:-ubuntu}"
+var_os="${var_os:-Ubuntu}"
 var_version="${var_version:-24.04}"
 var_arm64="${var_arm64:-no}"
 var_unprivileged="${var_unprivileged:-1}"