diff --git a/src/core/ddsc/include/ddsc/dds_public_qos.h b/src/core/ddsc/include/ddsc/dds_public_qos.h
index 187e03d..d78091f 100644
--- a/src/core/ddsc/include/ddsc/dds_public_qos.h
+++ b/src/core/ddsc/include/ddsc/dds_public_qos.h
@@ -195,6 +195,21 @@ void dds_qos_merge
     _In_ const dds_qos_t * __restrict src
 );
 
+/**
+ * @brief Copy all QoS-policies from one structure to another, unless already set
+ *
+ * Policies are copied from src to dst, unless src already has the policy set to a non-default value.
+ *
+ * @param[in,out] dst - Pointer to the destination qos structure
+ * @param[in] src - Pointer to the source qos structure
+ */
+DDS_EXPORT
+bool dds_qos_equal
+(
+    _In_ const dds_qos_t * __restrict a,
+    _In_ const dds_qos_t * __restrict b
+);
+
 /**
  * @brief Set the userdata of a qos structure.
  *
diff --git a/src/core/ddsc/src/dds_qos.c b/src/core/ddsc/src/dds_qos.c
index 805630f..fe1418f 100644
--- a/src/core/ddsc/src/dds_qos.c
+++ b/src/core/ddsc/src/dds_qos.c
@@ -244,16 +244,30 @@ void dds_qos_merge (
 {
     if(!src){
         DDS_ERROR(DDS_RETCODE_BAD_PARAMETER, "Argument source(src) is NULL");
-        return ;
+        return;
     }
     if(!dst){
         DDS_ERROR(DDS_RETCODE_BAD_PARAMETER, "Argument destination(dst) is NULL");
-        return ;
+        return;
     }
     /* Copy qos from source to destination unless already set */
     nn_xqos_mergein_missing (dst, src);
 }
 
+bool dds_qos_equal (
+    _In_opt_ const dds_qos_t * __restrict a,
+    _In_opt_ const dds_qos_t * __restrict b)
+{
+    /* FIXME: a bit of a hack - and I am not so sure I like accepting null pointers here anyway */
+    if (a == NULL && b == NULL) {
+        return true;
+    } else if (a == NULL || b == NULL) {
+        return false;
+    } else {
+        return nn_xqos_delta(a, b, ~(uint64_t)0) != 0;
+    }
+}
+
 void dds_qset_userdata(
     _Inout_ dds_qos_t * __restrict qos,
     _In_reads_bytes_opt_(sz) const void * __restrict value,
diff --git a/src/core/ddsc/src/dds_topic.c b/src/core/ddsc/src/dds_topic.c
index 683838b..9c2329e 100644
--- a/src/core/ddsc/src/dds_topic.c
+++ b/src/core/ddsc/src/dds_topic.c
@@ -153,7 +153,7 @@ dds_topic_status_cb(
 }
 
 sertopic_t
-dds_topic_lookup(
+dds_topic_lookup_locked(
         dds_domain *domain,
         const char *name)
 {
@@ -163,7 +163,6 @@ dds_topic_lookup(
     assert (domain);
     assert (name);
 
-    os_mutexLock (&dds_global.m_mutex);
     st = ut_avlIterFirst (&dds_topictree_def, &domain->m_topics, &iter);
     while (st) {
         if (strcmp (st->name, name) == 0) {
@@ -171,6 +170,17 @@ dds_topic_lookup(
         }
         st = ut_avlIterNext (&iter);
     }
+    return st;
+}
+
+sertopic_t
+dds_topic_lookup(
+        dds_domain *domain,
+        const char *name)
+{
+    sertopic_t st;
+    os_mutexLock (&dds_global.m_mutex);
+    st = dds_topic_lookup_locked(domain, name);
     os_mutexUnlock (&dds_global.m_mutex);
     return st;
 }
@@ -195,16 +205,14 @@ dds_topic_free(
 }
 
 static void
-dds_topic_add(
+dds_topic_add_locked(
         dds_domainid_t id,
         sertopic_t st)
 {
     dds_domain * dom;
-    os_mutexLock (&dds_global.m_mutex);
     dom = dds_domain_find_locked (id);
     assert (dom);
     ut_avlInsert (&dds_topictree_def, &dom->m_topics, st);
-    os_mutexUnlock (&dds_global.m_mutex);
 }
 
 _Pre_satisfies_((participant & DDS_ENTITY_KIND_MASK) == DDS_KIND_PARTICIPANT)
@@ -223,13 +231,15 @@ dds_find_topic(
     if (name) {
         rc = dds_entity_lock(participant, DDS_KIND_PARTICIPANT, &p);
         if (rc == DDS_RETCODE_OK) {
-            st = dds_topic_lookup (p->m_domain, name);
+            os_mutexLock (&dds_global.m_mutex);
+            st = dds_topic_lookup_locked (p->m_domain, name);
             if (st) {
                 dds_entity_add_ref (&st->status_cb_entity->m_entity);
                 tp = st->status_cb_entity->m_entity.m_hdl;
             } else {
                 tp = DDS_ERRNO(DDS_RETCODE_PRECONDITION_NOT_MET, "Topic is not being created yet");
             }
+            os_mutexUnlock (&dds_global.m_mutex);
             dds_entity_unlock(p);
         } else {
             tp = DDS_ERRNO(rc, "Error occurred on locking entity");
@@ -297,6 +307,17 @@ dds_topic_qos_set(
     return ret;
 }
 
+static bool dupdef_qos_ok(const dds_qos_t *qos, const struct sertopic *st)
+{
+    if ((qos == NULL) != (st->status_cb_entity->m_entity.m_qos == NULL)) {
+        return false;
+    } else if (qos == NULL) {
+        return true;
+    } else {
+        return dds_qos_equal(st->status_cb_entity->m_entity.m_qos, qos);
+    }
+}
+
 _Pre_satisfies_((participant & DDS_ENTITY_KIND_MASK) == DDS_KIND_PARTICIPANT)
 DDS_EXPORT dds_entity_t
 dds_create_topic(
@@ -353,97 +374,110 @@ dds_create_topic(
         }
     }
 
+    /* FIXME: I find it weird that qos may be NULL in the entity */
+
     /* Check if topic already exists with same name */
-    if (dds_topic_lookup (par->m_domain, name)) {
-        hdl = DDS_ERRNO(DDS_RETCODE_PRECONDITION_NOT_MET, "Precondition not met");
-        goto qos_err;
-    }
+    os_mutexLock (&dds_global.m_mutex);
+    if ((st = dds_topic_lookup_locked (par->m_domain, name)) != NULL) {
+        if (st->type != desc) {
+            /* FIXME: should copy the type, perhaps? but then the pointers will no longer be the same */
+            hdl = DDS_ERRNO(DDS_RETCODE_PRECONDITION_NOT_MET, "Create topic with mismatching type.");
+        } else if (!dupdef_qos_ok(qos, st)) {
+            /* FIXME: should copy the type, perhaps? but then the pointers will no longer be the same */
+            hdl = DDS_ERRNO(DDS_RETCODE_INCONSISTENT_POLICY, "Create topic with mismatching qos.");
+        } else {
+            dds_entity_add_ref (&st->status_cb_entity->m_entity);
+            hdl = st->status_cb_entity->m_entity.m_hdl;
+        }
+        os_mutexUnlock (&dds_global.m_mutex);
+    } else {
+        typename = desc->m_typename;
+        key = (char*) dds_alloc (strlen (name) + strlen (typename) + 2);
+        strcpy (key, name);
+        strcat (key, "/");
+        strcat (key, typename);
 
-    typename = desc->m_typename;
-    key = (char*) dds_alloc (strlen (name) + strlen (typename) + 2);
-    strcpy (key, name);
-    strcat (key, "/");
-    strcat (key, typename);
+        if (qos) {
+            new_qos = dds_qos_create();
+            /* Only returns failure when one of the qos args is NULL, which
+             * is not the case here. */
+            (void)dds_qos_copy(new_qos, qos);
+        }
 
-    if (qos) {
-        new_qos = dds_qos_create();
-        /* Only returns failure when one of the qos args is NULL, which
-         * is not the case here. */
-        (void)dds_qos_copy(new_qos, qos);
-    }
+        /* Create topic */
+        top = dds_alloc (sizeof (*top));
+        top->m_descriptor = desc;
+        hdl = dds_entity_init (&top->m_entity, par, DDS_KIND_TOPIC, new_qos, listener, DDS_TOPIC_STATUS_MASK);
+        top->m_entity.m_deriver.delete = dds_topic_delete;
+        top->m_entity.m_deriver.set_qos = dds_topic_qos_set;
+        top->m_entity.m_deriver.validate_status = dds_topic_status_validate;
 
-    /* Create topic */
-    top = dds_alloc (sizeof (*top));
-    top->m_descriptor = desc;
-    hdl = dds_entity_init (&top->m_entity, par, DDS_KIND_TOPIC, new_qos, listener, DDS_TOPIC_STATUS_MASK);
-    top->m_entity.m_deriver.delete = dds_topic_delete;
-    top->m_entity.m_deriver.set_qos = dds_topic_qos_set;
-    top->m_entity.m_deriver.validate_status = dds_topic_status_validate;
-
-    st = dds_alloc (sizeof (*st));
-    st->type = (void*) desc;
-    os_atomic_st32 (&st->refcount, 1);
-    st->status_cb = dds_topic_status_cb;
-    st->status_cb_entity = top;
-    st->name_typename = key;
-    st->name = dds_alloc (strlen (name) + 1);
-    strcpy (st->name, name);
-    st->typename = dds_alloc (strlen (typename) + 1);
-    strcpy (st->typename, typename);
-    st->nkeys = desc->m_nkeys;
-    st->keys = desc->m_keys;
-    st->id = next_topicid++;
+        st = dds_alloc (sizeof (*st));
+        st->type = (void*) desc;
+        os_atomic_st32 (&st->refcount, 1);
+        st->status_cb = dds_topic_status_cb;
+        st->status_cb_entity = top;
+        st->name_typename = key;
+        st->name = dds_alloc (strlen (name) + 1);
+        strcpy (st->name, name);
+        st->typename = dds_alloc (strlen (typename) + 1);
+        strcpy (st->typename, typename);
+        st->nkeys = desc->m_nkeys;
+        st->keys = desc->m_keys;
+        st->id = next_topicid++;
 
 #ifdef VXWORKS_RTP
-    st->hash = (st->id * UINT64_C (12844332200329132887UL)) >> 32;
+        st->hash = (st->id * UINT64_C (12844332200329132887UL)) >> 32;
 #else
-    st->hash = (st->id * UINT64_C (12844332200329132887)) >> 32;
+        st->hash = (st->id * UINT64_C (12844332200329132887)) >> 32;
 #endif
 
-    /* Check if topic cannot be optimised (memcpy marshal) */
+        /* Check if topic cannot be optimised (memcpy marshal) */
 
-    if ((desc->m_flagset & DDS_TOPIC_NO_OPTIMIZE) == 0) {
-        st->opt_size = dds_stream_check_optimize (desc);
-    }
-    top->m_stopic = st;
-
-    /* Add topic to extent */
-    dds_topic_add (par->m_domainid, st);
-
-    nn_plist_init_empty (&plist);
-    if (new_qos) {
-        dds_qos_merge (&plist.qos, new_qos);
-    }
-
-    /* Set Topic meta data (for SEDP publication) */
-    plist.qos.topic_name = dds_string_dup (st->name);
-    plist.qos.type_name = dds_string_dup (st->typename);
-    plist.qos.present |= (QP_TOPIC_NAME | QP_TYPE_NAME);
-    if (desc->m_meta) {
-        plist.type_description = dds_string_dup (desc->m_meta);
-        plist.present |= PP_PRISMTECH_TYPE_DESCRIPTION;
-    }
-    if (desc->m_nkeys) {
-        plist.qos.present |= QP_PRISMTECH_SUBSCRIPTION_KEYS;
-        plist.qos.subscription_keys.use_key_list = 1;
-        plist.qos.subscription_keys.key_list.n = desc->m_nkeys;
-        plist.qos.subscription_keys.key_list.strs = dds_alloc (desc->m_nkeys * sizeof (char*));
-        for (index = 0; index < desc->m_nkeys; index++) {
-            plist.qos.subscription_keys.key_list.strs[index] = dds_string_dup (desc->m_keys[index].m_name);
+        if ((desc->m_flagset & DDS_TOPIC_NO_OPTIMIZE) == 0) {
+            st->opt_size = dds_stream_check_optimize (desc);
         }
-    }
+        top->m_stopic = st;
 
-    /* Publish Topic */
-    if (asleep) {
-        thread_state_awake (thr);
+        /* Add topic to extent */
+        dds_topic_add_locked (par->m_domainid, st);
+        os_mutexUnlock (&dds_global.m_mutex);
+
+        nn_plist_init_empty (&plist);
+        if (new_qos) {
+            dds_qos_merge (&plist.qos, new_qos);
+        }
+
+        /* Set Topic meta data (for SEDP publication) */
+        plist.qos.topic_name = dds_string_dup (st->name);
+        plist.qos.type_name = dds_string_dup (st->typename);
+        plist.qos.present |= (QP_TOPIC_NAME | QP_TYPE_NAME);
+        if (desc->m_meta) {
+            plist.type_description = dds_string_dup (desc->m_meta);
+            plist.present |= PP_PRISMTECH_TYPE_DESCRIPTION;
+        }
+        if (desc->m_nkeys) {
+            plist.qos.present |= QP_PRISMTECH_SUBSCRIPTION_KEYS;
+            plist.qos.subscription_keys.use_key_list = 1;
+            plist.qos.subscription_keys.key_list.n = desc->m_nkeys;
+            plist.qos.subscription_keys.key_list.strs = dds_alloc (desc->m_nkeys * sizeof (char*));
+            for (index = 0; index < desc->m_nkeys; index++) {
+                plist.qos.subscription_keys.key_list.strs[index] = dds_string_dup (desc->m_keys[index].m_name);
+            }
+        }
+
+        /* Publish Topic */
+        if (asleep) {
+            thread_state_awake (thr);
+        }
+        ddsi_pp = ephash_lookup_participant_guid (&par->m_guid);
+        assert (ddsi_pp);
+        sedp_write_topic (ddsi_pp, &plist);
+        if (asleep) {
+            thread_state_asleep (thr);
+        }
+        nn_plist_fini (&plist);
     }
-    ddsi_pp = ephash_lookup_participant_guid (&par->m_guid);
-    assert (ddsi_pp);
-    sedp_write_topic (ddsi_pp, &plist);
-    if (asleep) {
-        thread_state_asleep (thr);
-    }
-    nn_plist_fini (&plist);
 
 qos_err:
     dds_entity_unlock(par);
diff --git a/src/core/ddsc/tests/topic.c b/src/core/ddsc/tests/topic.c
index 68f82b0..08d539f 100644
--- a/src/core/ddsc/tests/topic.c
+++ b/src/core/ddsc/tests/topic.c
@@ -125,9 +125,12 @@ Test(ddsc_topic_create, non_participants, .init=ddsc_topic_init, .fini=ddsc_topi
 Test(ddsc_topic_create, duplicate, .init=ddsc_topic_init, .fini=ddsc_topic_fini)
 {
     dds_entity_t topic;
-    /* Creating the same topic should fail.  */
+    dds_return_t ret;
+    /* Creating the same topic should succeed.  */
     topic = dds_create_topic(g_participant, &RoundTripModule_DataType_desc, g_topicRtmDataTypeName, NULL, NULL);
-    cr_assert_eq(dds_err_nr(topic), DDS_RETCODE_PRECONDITION_NOT_MET, "returned %s", dds_err_str(topic));
+    cr_assert_gt(topic, 0, "returned %s", dds_err_str(topic));
+    ret = dds_delete(topic);
+    cr_assert_eq(ret, DDS_RETCODE_OK);
 }
 /*************************************************************************************************/