diff --git a/cluster/gke/util.sh b/cluster/gke/util.sh
index 59d532a9cf0..54dfc410f5c 100755
--- a/cluster/gke/util.sh
+++ b/cluster/gke/util.sh
@@ -104,6 +104,18 @@ function verify-prereqs() {
   ${sudo_prefix} gcloud ${gcloud_prompt:-} components update || true
 }
 
+# Validate a kubernetes cluster
+function validate-cluster {
+  # Simply override the NUM_NODES variable if we've spread nodes across multiple
+  # zones before calling into the generic validate-cluster logic.
+  local EXPECTED_NUM_NODES="${NUM_NODES}"
+  for zone in $(echo "${ADDITIONAL_ZONES}" | sed "s/,/ /g")
+  do
+    (( EXPECTED_NUM_NODES += NUM_NODES ))
+  done
+  NUM_NODES=${EXPECTED_NUM_NODES} bash -c "${KUBE_ROOT}/cluster/validate-cluster.sh"
+}
+
 # Instantiate a kubernetes cluster
 #
 # Assumed vars:
@@ -224,6 +236,9 @@ function detect-nodes() {
 
 # Detect minions created in the minion group
 #
+# Note that this will only return the nodes from one of the cluster's instance
+# groups, regardless of how many the cluster has.
+#
 # Assumed vars:
 #   none
 # Vars set:
@@ -242,7 +257,10 @@ function detect-node-names {
   echo "NODE_NAMES=${NODE_NAMES[*]}"
 }
 
-# Detect instance group name generated by gke
+# Detect instance group name generated by gke.
+#
+# Note that this will only select instance groups in the same zone as the
+# cluster, meaning that it won't include all groups in a multi-zone cluster.
 #
 # Assumed vars:
 #   GCLOUD
@@ -255,7 +273,7 @@ function detect-node-instance-group {
   echo "... in gke:detect-node-instance-group()" >&2
   NODE_INSTANCE_GROUP=$("${GCLOUD}" ${CMD_GROUP:-} container clusters describe \
     --project="${PROJECT}" --zone="${ZONE}" "${CLUSTER_NAME}" \
-    | grep instanceGroupManagers | cut -d '/' -f 11)
+    | grep instanceGroupManagers | grep "${ZONE}" | cut -d '/' -f 11)
 }
 
 # SSH to a node by name ($1) and run a command ($2).