diff --git a/examples/chart/teleport-cluster/templates/proxy/config.yaml b/examples/chart/teleport-cluster/templates/proxy/config.yaml
index 0d98cb99ce149..8cd7788ad0c47 100644
--- a/examples/chart/teleport-cluster/templates/proxy/config.yaml
+++ b/examples/chart/teleport-cluster/templates/proxy/config.yaml
@@ -1,5 +1,8 @@
 {{- $proxy := mustMergeOverwrite (mustDeepCopy .Values) .Values.proxy -}}
 {{- $configTemplate := printf "teleport-cluster.proxy.config.%s" $proxy.chartMode -}}
+{{- if (contains ":" $proxy.clusterName) -}}
+  {{- fail "clusterName must not contain a colon, you can override the cluster's public address with publicAddr" -}}
+{{- end -}}
 apiVersion: v1
 kind: ConfigMap
 metadata:
diff --git a/examples/chart/teleport-cluster/tests/__snapshot__/proxy_config_test.yaml.snap b/examples/chart/teleport-cluster/tests/__snapshot__/proxy_config_test.yaml.snap
index ea55919113818..7765a078da150 100644
--- a/examples/chart/teleport-cluster/tests/__snapshot__/proxy_config_test.yaml.snap
+++ b/examples/chart/teleport-cluster/tests/__snapshot__/proxy_config_test.yaml.snap
@@ -1,3 +1,33 @@
+generates a config with a clusterName containing a regular string:
+  1: |
+    |-
+      auth_service:
+        enabled: false
+      proxy_service:
+        enabled: true
+        kube_listen_addr: 0.0.0.0:3026
+        listen_addr: 0.0.0.0:3023
+        mysql_listen_addr: 0.0.0.0:3036
+        public_addr: helm-test.example.com:443
+        tunnel_listen_addr: 0.0.0.0:3024
+      ssh_service:
+        enabled: false
+      teleport:
+        auth_server: RELEASE-NAME-auth.NAMESPACE.svc.cluster.local:3025
+        join_params:
+          method: kubernetes
+          token_name: RELEASE-NAME-proxy
+        log:
+          format:
+            extra_fields:
+            - timestamp
+            - level
+            - component
+            - caller
+            output: text
+          output: stderr
+          severity: INFO
+      version: v3
 matches snapshot for acme-on.yaml:
   1: |
     |-
diff --git a/examples/chart/teleport-cluster/tests/proxy_config_test.yaml b/examples/chart/teleport-cluster/tests/proxy_config_test.yaml
index 23727d44cc07c..3c6b93938204f 100644
--- a/examples/chart/teleport-cluster/tests/proxy_config_test.yaml
+++ b/examples/chart/teleport-cluster/tests/proxy_config_test.yaml
@@ -137,3 +137,28 @@ tests:
           of: ConfigMap
       - matchSnapshot:
           path: data.teleport\.yaml
+
+  - it: generates a config with a clusterName containing a regular string
+    set:
+      clusterName: "helm-test.example.com"
+    asserts:
+      - hasDocuments:
+          count: 1
+      - isKind:
+          of: ConfigMap
+      - matchSnapshot:
+          path: data.teleport\.yaml
+
+  - it: fails when clusterName contains a regular string and a colon
+    set:
+      clusterName: "helm-test:cluster-1"
+    asserts:
+      - failedTemplate:
+          errorMessage: "clusterName must not contain a colon, you can override the cluster's public address with publicAddr"
+
+  - it: fails when clusterName contains a port
+    set:
+      clusterName: "helm-test.example.com:443"
+    asserts:
+      - failedTemplate:
+          errorMessage: "clusterName must not contain a colon, you can override the cluster's public address with publicAddr"