diff --git a/act-runner/rebuild.bash b/act-runner/rebuild.bash
index 2157ebf..eb9af28 100644
--- a/act-runner/rebuild.bash
+++ b/act-runner/rebuild.bash
@@ -20,6 +20,7 @@ BUTANE_CONFIG="${CONFIG_PATH}/act-runner.bu"
 VCPUS="8"
 RAM_MB="16132"
 DISK_GB="100"
+SSH_KEY="${HOME}/.ssh/_${HOSTNAME}_act_runner_ed25519"
 
 IGNITION_PATH="${CONFIG_PATH}/${NAME}.ign"
 IMAGE_PATH="${CONFIG_PATH}/${NAME}.qcow2"
@@ -59,7 +60,11 @@ download_image=$(command ls "${download_dir}"/*.qcow2)
 mv "${download_image}" "${IMAGE_PATH}"
 
 echo "${HOSTNAME}-act-runner" >"${CONFIG_PATH}/hostname"
-cat ~/.ssh/*.pub >"${CONFIG_PATH}/core_ssh_keys.pub"
+
+if [ ! -f "${SSH_KEY}" ]; then
+  ssh-keygen -q -f "${SSH_KEY}" -t ed25519 -C "${USERNAME}@${HOSTNAME}-act-runner" -N ''
+fi
+cp "${SSH_KEY}.pub" "${CONFIG_PATH}/core_ssh_keys.pub"
 
 mkdir --parents "${CONFIG_PATH}/host_keys"