diff --git a/README.md b/README.md
index 018af72..318fd48 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,9 @@ ddev nightwatch --tag core
 
 ## Nightwatch Examples
 
-You can watch Nightwatch running in real time at https://drupal.ddev.site:7900 for Chrome and https://drupal.ddev.site:7901 for Firefox. The password is "secret".
+You can watch Nightwatch running in real time at https://drupal.ddev.site:7900
+for Chrome and https://drupal.ddev.site:7901 for Firefox. The password is
+"secret". YMMV using Firefox as core tests don't currently run on it.
 
 Only core tests
 ```
diff --git a/docker-compose.core-dev-selenium.yaml b/docker-compose.core-dev-selenium.yaml
index 33330ae..9dc91ef 100644
--- a/docker-compose.core-dev-selenium.yaml
+++ b/docker-compose.core-dev-selenium.yaml
@@ -30,9 +30,11 @@ services:
     expose:
       - 7901
     environment:
+      - NO_VNC_PORT=7901
+      - SE_NO_VNC_PORT=7901
       - VIRTUAL_HOST=$DDEV_HOSTNAME
-      - HTTPS_EXPOSE=7900:7901
-      - HTTP_EXPOSE=7910:7901
+      - HTTPS_EXPOSE=7901:7901
+      - HTTP_EXPOSE=7911:7901
     links:
       - web:web
     external_links: