--- a/browser/extensions/clicktoplay-rollout/bootstrap.js
+++ b/browser/extensions/clicktoplay-rollout/bootstrap.js
@@ -66,16 +66,18 @@ function defineCohort() {
         // intentionally missing from the list is STATE_ENABLED,
         // which will keep cohort undefined.
         break;
     }
   }
 
   switch (cohort) {
     case undefined:
+    case null:
+    case "":
     case "test":
     case "control":
     case "excluded":
     {
       // If it's either test/control, the cohort might have changed
       // if the desired sampling has been changed.
       let testThreshold = TEST_THRESHOLD[updateChannel];
       let userSample = getUserSample();