diff --git a/README.md b/README.md
index 8a21130a..9211839c 100644
--- a/README.md
+++ b/README.md
@@ -100,7 +100,7 @@ minikube, change all instances of LoadBalancer services to NodePort.
 ```
 
 Save the external IP addresses of controller and router services in
-FISSION_URL and FISSION_ROUTER, respectively.  FISSION_URL is used by
+FISSION_URL and FISSION_ROUTER, respectively. FISSION_URL should be prefixed with a `http://`.  FISSION_URL is used by
 the fission CLI to find the server.  (FISSION_ROUTER is only needed
 for the examples below to work.)