diff --git a/docs/08-docker/03-customize-docker-images.mdx b/docs/08-docker/03-customize-docker-images.mdx
index 287b2ea7..6a7819ab 100644
--- a/docs/08-docker/03-customize-docker-images.mdx
+++ b/docs/08-docker/03-customize-docker-images.mdx
@@ -119,7 +119,7 @@ based on unityci/editor and install blender on top of it.
 ### Dockerfile
 
 ```dockerfile
-ARG GAMECI_IMAGE = unityci/editor:2021.3.1f1-windows-mono-1.0.1
+ARG GAMECI_IMAGE=unityci/editor:2021.3.1f1-windows-mono-1.0.1
 FROM $GAMECI_IMAGE
 
 ARG BLENDER_SHORT_VERSION=3.4