diff --git a/cluster/gce/config-test.sh b/cluster/gce/config-test.sh
index 44a51d845a7..11ed986eb8d 100755
--- a/cluster/gce/config-test.sh
+++ b/cluster/gce/config-test.sh
@@ -22,7 +22,7 @@ MASTER_SIZE=${MASTER_SIZE:-g1-small}
 MINION_SIZE=${MINION_SIZE:-g1-small}
 NUM_MINIONS=${NUM_MINIONS:-2}
 MINION_DISK_TYPE=pd-standard
-MINION_DISK_SIZE=100GB
+MINION_DISK_SIZE=${MINION_DISK_SIZE:-100GB}
 # TODO(dchen1107): Filed an internal issue to create an alias
 # for containervm image, so that gcloud will expand this
 # to the latest supported image.