diff --git a/contrib/docker/README.md b/contrib/docker/README.md
index 27e25afcef..221d9c53b5 100644
--- a/contrib/docker/README.md
+++ b/contrib/docker/README.md
@@ -12,7 +12,7 @@ use that server.
 Build the docker image with the `docker build` command from the root of the synapse repository.
 
 ```
-docker build -t matrixdotorg/synapse .
+docker build -t docker.io/matrixdotorg/synapse .
 ```
 
 The `-t` option sets the image tag. Official images are tagged `matrixdotorg/synapse:<version>` where `<version>` is the same as the release tag in the synapse git repository.