diff --git a/src/iothread.c b/src/iothread.c
index cf28f6db2f..a170317911 100644
--- a/src/iothread.c
+++ b/src/iothread.c
@@ -51,17 +51,18 @@ void enqueuePendingClientsToMainThread(client *c, int unbind) {
     if (unbind) connUnbindEventLoop(c->conn);
     /* Just skip if it already is transferred. */
     if (c->io_thread_client_list_node) {
+        IOThread *t = &IOThreads[c->tid];
         /* If there are several clients to process, let the main thread handle them ASAP.
          * Since the client being added to the queue may still need to be processed by
          * the IO thread, we must call this before adding it to the queue to avoid
          * races with the main thread. */
-        sendPendingClientsToMainThreadIfNeeded(&IOThreads[c->tid], 1);
-        /* Remove the client from clients list of IO thread. */
-        listDelNode(IOThreads[c->tid].clients, c->io_thread_client_list_node);
-        c->io_thread_client_list_node = NULL;
+        sendPendingClientsToMainThreadIfNeeded(t, 1);
         /* Disable read and write to avoid race when main thread processes. */
         c->io_flags &= ~(CLIENT_IO_READ_ENABLED | CLIENT_IO_WRITE_ENABLED);
-        listAddNodeTail(IOThreads[c->tid].pending_clients_to_main_thread, c);
+        /* Remove the client from IO thread, add it to main thread's pending list. */
+        listUnlinkNode(t->clients, c->io_thread_client_list_node);
+        listLinkNodeTail(t->pending_clients_to_main_thread, c->io_thread_client_list_node);
+        c->io_thread_client_list_node = NULL;
     }
 }
 
@@ -544,7 +545,8 @@ int processClientsFromMainThread(IOThread *t) {
 
         /* Link client in IO thread clients list first. */
         serverAssert(c->io_thread_client_list_node == NULL);
-        listAddNodeTail(t->clients, c);
+        listUnlinkNode(t->processing_clients, ln);
+        listLinkNodeTail(t->clients, ln);
         c->io_thread_client_list_node = listLast(t->clients);
 
         /* The client now is in the IO thread, let's free deferred objects. */
@@ -575,7 +577,8 @@ int processClientsFromMainThread(IOThread *t) {
             }
         }
     }
-    listEmpty(t->processing_clients);
+    /* All clients must are processed. */
+    serverAssert(listLength(t->processing_clients) == 0);
     return processed;
 }