diff --git a/src/gui/plugins/entity_tree/EntityTree.cc b/src/gui/plugins/entity_tree/EntityTree.cc
index 8a0ae74152..79de5dfb7f 100644
--- a/src/gui/plugins/entity_tree/EntityTree.cc
+++ b/src/gui/plugins/entity_tree/EntityTree.cc
@@ -132,6 +132,13 @@ void TreeModel::AddEntity(unsigned int _entity, const QString &_entityName,
     return;
   }
 
+  if (this->entityItems.find(_entity) != this->entityItems.end())
+  {
+    ignwarn << "Internal error: Trying to create item for entity [" << _entity
+            << "], but entity already has an item." << std::endl;
+    return;
+  }
+
   // New entity item
   auto entityItem = new QStandardItem(_entityName);
   entityItem->setData(_entityName, this->roleNames().key("entityName"));