diff --git a/src/common/interfaceregistry.c b/src/common/interfaceregistry.c
index 75e05c17b..0b2959d13 100644
--- a/src/common/interfaceregistry.c
+++ b/src/common/interfaceregistry.c
@@ -189,9 +189,20 @@ lumiera_interfaceregistry_bulkremove_interfaces (LumieraInterface* self)
           TRACE (interfaceregistry, "interface %s, version %d, instance %s", (*self)->interface, (*self)->version, (*self)->name);
 
           LumieraInterfacenode node = (LumieraInterfacenode) psplay_find (lumiera_interfaceregistry, *self, 0);
-          REQUIRE (node->refcnt == 0, "but is %d", node->refcnt);
-
-          lumiera_interfacenode_delete ((LumieraInterfacenode) psplay_remove (lumiera_interfaceregistry, &node->node));
+          if (node)
+            {
+              REQUIRE (node->refcnt == 0, "but is %d", node->refcnt);
+              lumiera_interfacenode_delete ((LumieraInterfacenode) psplay_remove (lumiera_interfaceregistry, &node->node));
+            }
+          else
+            {
+              ///////////TICKET #864 : should not happen but does happen in practice, e.g. when there is a copy or another library linked against that module
+              ///////////              Guess the pluginloader should not have added the duplicate into the interfaceregistry on discovery.
+              
+              WARN (interfaceregistry, "ENTRY NOT FOUND in interfaceregistry at clean-up of interface %s, instance %s"
+                                     , (*self)->interface
+                                     , (*self)->name);
+            }
 
           ++self;
         }