diff --git a/frontend/src/scenes/settings/environment/proxyLogic.ts b/frontend/src/scenes/settings/environment/proxyLogic.ts
index d18a07babbf61..e087aee0aa616 100644
--- a/frontend/src/scenes/settings/environment/proxyLogic.ts
+++ b/frontend/src/scenes/settings/environment/proxyLogic.ts
@@ -83,6 +83,8 @@ export const proxyLogic = kea<proxyLogicType>([
                     ? 'Domains cannot include wildcards'
                     : !isDomain('http://' + domain)
                     ? 'Do not include the protocol e.g. https://'
+                    : !domain.match(/^[a-z0-9](?:[a-z0-9.-]*[a-z0-9])?$/)
+                    ? "Invalid domain. Please provide a lowercase RFC 1123 subdomain. It must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character"
                     : undefined,
             }),
             submit: ({ domain }) => {