diff --git a/lib/sidekiq/manager.rb b/lib/sidekiq/manager.rb
index a73f0403..822cd23d 100644
--- a/lib/sidekiq/manager.rb
+++ b/lib/sidekiq/manager.rb
@@ -132,7 +132,7 @@ module Sidekiq
     # get handle to the underlying thread performing work for a processor
     # so we have it call us and tell us.
     def real_thread(proxy_id, thr)
-      @threads[proxy_id] = thr
+      @threads[proxy_id] = thr if thr.alive?
     end
 
     PROCTITLES = [