--- a/browser/extensions/e10srollout/bootstrap.js
+++ b/browser/extensions/e10srollout/bootstrap.js
@@ -87,16 +87,19 @@ function getUserSample() {
 
   let val = Math.floor(Math.random() * 100);
   Preferences.set(PREF_COHORT_SAMPLE, val);
   return val;
 }
 
 function setCohort(cohortName) {
   Preferences.set(PREF_COHORT_NAME, cohortName);
+  try {
+    Services.appinfo.annotateCrashReport("E10SCohort", cohortName);
+  } catch (e) {}
 }
 
 function optedIn() {
   return Preferences.get(PREF_E10S_OPTED_IN, false) ||
          Preferences.get(PREF_E10S_FORCE_ENABLED, false);
 }
 
 function optedOut() {