diff --git a/src/core/ddsi/src/q_entity.c b/src/core/ddsi/src/q_entity.c
index a199f63..b15b807 100644
--- a/src/core/ddsi/src/q_entity.c
+++ b/src/core/ddsi/src/q_entity.c
@@ -4598,6 +4598,13 @@ void proxy_writer_set_alive_may_unlock (struct proxy_writer *pwr, bool notify)
      heap). */
   assert (!pwr->alive);
 
+  /* check that proxy writer still exists (when deleting it is removed from guid hash) */
+  if (ephash_lookup_proxy_writer_guid (pwr->e.gv->guid_hash, &pwr->e.guid) == NULL)
+  {
+    ELOGDISC (pwr, "proxy_writer_set_alive_may_unlock("PGUIDFMT") - not in guid_hash, pwr deleting\n", PGUID (pwr->e.guid));
+    return;
+  }
+
   ddsrt_mutex_lock (&pwr->c.proxypp->e.lock);
   pwr->alive = true;
   pwr->alive_vclock++;