diff --git a/cluster/kube/lib/calico.libsonnet b/cluster/kube/lib/calico.libsonnet
index 6a9b799..d580197 100644
--- a/cluster/kube/lib/calico.libsonnet
+++ b/cluster/kube/lib/calico.libsonnet
@@ -278,6 +278,10 @@
                                     CNI_NETWORK_CONFIG: kube.ConfigMapRef(env.cm, "cni_network_config"),
                                     ETCD_ENDPOINTS: kube.ConfigMapRef(env.cm, "etcd_endpoints"),
                                     CNI_MTU: kube.ConfigMapRef(env.cm, "veth_mtu"),
+                                    # Important: our directory is changed from the default (/etc/cni/net.d)
+                                    # to inside /opt/ above in the cni_config HostPathVolume.
+                                    # See projectcalico/cni-plugin//k8s-install/scripts/install-cni.sh:24 for reference.
+                                    CNI_NET_DIR: "/opt/cni/conf",
                                     # TODO(implr) needed?
                                     CNI_CONF_ETCD_CA_CERT_FILE: kube.ConfigMapRef(env.cm, "etcd_ca"),
                                     CNI_CONF_ETCD_KEY_FILE: kube.ConfigMapRef(env.cm, "etcd_key"),