diff --git a/maestro/subscription_registry.c b/maestro/subscription_registry.c
index bd2bf0884caa2f5a3495dd378f0e22923862c199..9ffb9f85ebe2f20bcfb5915f1b53661d92af2cff 100644
--- a/maestro/subscription_registry.c
+++ b/maestro/subscription_registry.c
@@ -1746,7 +1746,7 @@ mstro_pool_event_advertise(Mstro__Pool__Event *ev,
                   = atomic_fetch_add_explicit(nr_outstanding_acks,
                                               1, memory_order_release);
               DEBUG("Now %" PRIu64 " outstanding acks for this event\n",
-                    num_outstanding);
+                    num_outstanding+1);
 
               mstro_event ack_event;
               status = mstro_event_create(g_subscription_table.edom,