--- a/services/sync/tests/unit/test_syncscheduler.js
+++ b/services/sync/tests/unit/test_syncscheduler.js
@@ -834,19 +834,19 @@ add_task(async function test_sync_X_Weav
   // Sanity check that we picked the right value for BACKOFF:
   do_check_true(scheduler.syncInterval < BACKOFF * 1000);
 
   // Turn on server maintenance and sync again.
   serverBackoff = true;
   Service.sync();
 
   do_check_true(Status.backoffInterval >= BACKOFF * 1000);
-  // Allowing 3 seconds worth of of leeway between when Status.minimumNextSync
+  // Allowing 20 seconds worth of of leeway between when Status.minimumNextSync
   // was set and when this line gets executed.
-  let minimumExpectedDelay = (BACKOFF - 3) * 1000;
+  let minimumExpectedDelay = (BACKOFF - 20) * 1000;
   do_check_true(Status.minimumNextSync >= Date.now() + minimumExpectedDelay);
 
   // Verify that the next sync is actually going to wait that long.
   do_check_true(scheduler.nextSync >= Date.now() + minimumExpectedDelay);
   do_check_true(scheduler.syncTimer.delay >= minimumExpectedDelay);
 
   await cleanUpAndGo(server);
 });