1 files changed, 6 insertions, 0 deletions
diff --git a/entityx/Entity.h b/entityx/Entity.h
index 9fcf676..e4a3871 100644
--- a/entityx/Entity.h
+++ b/entityx/Entity.h
@@ -1079,5 +1079,11 @@ template <> struct hash<entityx::Entity> {
     return static_cast<std::size_t>(entity.id().index() ^ entity.id().version());
   }
 };
+
+template <> struct hash<const entityx::Entity> {
+  std::size_t operator () (const entityx::Entity &entity) const {
+    return static_cast<std::size_t>(entity.id().index() ^ entity.id().version());
+  }
+};
 }