diff --git a/src/core/surface/completion_queue.c b/src/core/surface/completion_queue.c
index c4b8d60782f..6a1d83ce5d4 100644
--- a/src/core/surface/completion_queue.c
+++ b/src/core/surface/completion_queue.c
@@ -71,6 +71,7 @@ struct grpc_completion_queue {
   grpc_pollset pollset;
   /* 0 initially, 1 once we've begun shutting down */
   int shutdown;
+  int shutdown_called;
   /* Head of a linked list of queued events (prev points to the last element) */
   event *queue;
   /* Fixed size chained hash table of events for pluck() */
@@ -107,7 +108,6 @@ static event *add_locked(grpc_completion_queue *cc, grpc_completion_type type,
                          grpc_event_finish_func on_finish, void *user_data) {
   event *ev = gpr_malloc(sizeof(event));
   gpr_uintptr bucket = ((gpr_uintptr)tag) % NUM_TAG_BUCKETS;
-  GPR_ASSERT(!cc->shutdown);
   ev->base.type = type;
   ev->base.tag = tag;
   ev->base.call = call;
@@ -150,6 +150,7 @@ static void end_op_locked(grpc_completion_queue *cc,
 #endif
   if (gpr_unref(&cc->refs)) {
     GPR_ASSERT(!cc->shutdown);
+    GPR_ASSERT(cc->shutdown_called);
     cc->shutdown = 1;
     gpr_cv_broadcast(GRPC_POLLSET_CV(&cc->pollset));
   }
@@ -380,6 +381,10 @@ grpc_event *grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
 /* Shutdown simply drops a ref that we reserved at creation time; if we drop
    to zero here, then enter shutdown mode and wake up any waiters */
 void grpc_completion_queue_shutdown(grpc_completion_queue *cc) {
+  gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
+  cc->shutdown_called = 1;
+  gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+
   if (gpr_unref(&cc->refs)) {
     gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
     GPR_ASSERT(!cc->shutdown);