diff --git a/docs/ad_hoc_gcp.md b/docs/ad_hoc_gcp.md
index 1ad2b7e..2493fcd 100644
--- a/docs/ad_hoc_gcp.md
+++ b/docs/ad_hoc_gcp.md
@@ -7,7 +7,7 @@ gcloud compute instances create testnet-explorer \
 --subnet=default \
 --network-tier=PREMIUM \
 --tags=https-server \
---image=debian-9 \
+--image-family=debian-9 \
 --image-project=debian-cloud \
 --boot-disk-size=24GB \
 --boot-disk-type=pd-standard \