diff --git a/docs/src/main/asciidoc/spring-cloud-config.adoc b/docs/src/main/asciidoc/spring-cloud-config.adoc
index a6479e59..60e8a5d2 100644
--- a/docs/src/main/asciidoc/spring-cloud-config.adoc
+++ b/docs/src/main/asciidoc/spring-cloud-config.adoc
@@ -1514,7 +1514,7 @@ The net result of this behavior is that all client applications that want to con
 [[discovery-first-bootstrap]]
 ==== Discovery First Lookup
 
-WARNING: Unless you are using <<config-first-bootstrap, config first bootstrap>>, you will need to have a `spring.config.import` property in your configuration properties.
+WARNING: Unless you are using <<config-first-bootstrap, config first bootstrap>>, you will need to have a `spring.config.import` property in your configuration properties with an `optional:` prefix.
 For example, `spring.config.import=optional:configserver:`.
 
 If you use a `DiscoveryClient` implementation, such as Spring Cloud Netflix and Eureka Service Discovery or Spring Cloud Consul, you can have the Config Server register with the Discovery Service.