diff --git a/README.md b/README.md
index 5bbdfb7a..ad25caee 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ docker run --publish 8000:80 ghcr.io/mermaid-js/mermaid-live-editor
 
 ### To configure renderer URL
 
-Set the Environment variable MERMAID_RENDERER_URL to the rendering service.
+When building, Set the Environment variable MERMAID_RENDERER_URL to the rendering service.
 Default is `https://mermaid.ink`
 
 ### Development