diff --git a/cluster/kubemark/config-default.sh b/cluster/kubemark/config-default.sh
index ec9831fb660..4158d1fde5e 100644
--- a/cluster/kubemark/config-default.sh
+++ b/cluster/kubemark/config-default.sh
@@ -28,6 +28,7 @@ NUM_NODES=${NUM_NODES:-100}
 MASTER_SIZE=${MASTER_SIZE:-n1-standard-$(get-master-size)}
 MASTER_DISK_TYPE=pd-ssd
 MASTER_DISK_SIZE=${MASTER_DISK_SIZE:-20GB}
+MASTER_ROOT_DISK_SIZE=${KUBEMARK_MASTER_ROOT_DISK_SIZE:-10GB}
 REGISTER_MASTER_KUBELET=${REGISTER_MASTER:-false}
 PREEMPTIBLE_NODE=${PREEMPTIBLE_NODE:-false}
 
diff --git a/test/kubemark/start-kubemark.sh b/test/kubemark/start-kubemark.sh
index 18f8b4df4b3..046f714b723 100755
--- a/test/kubemark/start-kubemark.sh
+++ b/test/kubemark/start-kubemark.sh
@@ -97,6 +97,7 @@ run-gcloud-compute-with-retries instances create "${MASTER_NAME}" \
   --tags "${MASTER_TAG}" \
   --network "${NETWORK}" \
   --scopes "storage-ro,compute-rw,logging-write" \
+  --boot-disk-size "${MASTER_ROOT_DISK_SIZE}" \
   --disk "name=${MASTER_NAME}-pd,device-name=master-pd,mode=rw,boot=no,auto-delete=no"
 
 run-gcloud-compute-with-retries firewall-rules create "${INSTANCE_PREFIX}-kubemark-master-https" \