diff --git a/libs/ecs/source/container.cpp b/libs/ecs/source/container.cpp
index 6e74ba5f..30708fcf 100644
--- a/libs/ecs/source/container.cpp
+++ b/libs/ecs/source/container.cpp
@@ -1,4 +1,5 @@
 #include <psemek/ecs/container.hpp>
+#include <psemek/util/assert.hpp>
 
 namespace psemek::ecs
 {
@@ -10,12 +11,14 @@ namespace psemek::ecs
 
 	void container::destroy(handle const & entity)
 	{
+		assert(alive(entity));
 		do_destroy(entity);
 		entity_list_.destroy(entity.id);
 	}
 
 	accessor container::get(handle const & entity)
 	{
+		assert(alive(entity));
 		auto const data = entity_list_.get_entities()[entity.id];
 		return {data.table, data.row};
 	}