diff --git a/Docker.wiki b/Docker.wiki
index 57b51f8..6ae9219 100644
--- a/Docker.wiki
+++ b/Docker.wiki
@@ -8,7 +8,7 @@
 = Details =
 
    * run `make docker` to enter the pre-built docker container.
-
    * run `make local-docker` to build a new local docker image.
+   * the 'docker' user must be able to read your source tree.
 
    * Use http://askubuntu.com/questions/477551/how-can-i-use-docker-without-sudo so you don't have to use root to access the container.
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