diff --git a/circle.yml b/circle.yml
index 7bca0d1..c2106ab 100644
--- a/circle.yml
+++ b/circle.yml
@@ -38,6 +38,8 @@
     # imagemagick is installed to give us access to the
     # `convert` tool to stitch together the screenshots.
     - sudo apt-get update; sudo apt-get install imagemagick
+    - "test $SAUCE_USERNAME && test $SAUCE_ACCESS_KEY
+       # Sauce Labs credentials required. Sign up here: https://saucelabs.com/opensauce/"
     - ? |-
         mkdir -p ~/sauce-connect
         cd ~/sauce-connect