diff --git a/meson.build b/meson.build
index b26bdcc..3317d5c 100644
--- a/meson.build
+++ b/meson.build
@@ -1,6 +1,7 @@
 project('DECS', 'd')
 
 src = [
+	'source/ecs/atomic.d',
 	'source/ecs/attributes.d',
 	'source/ecs/block_allocator.d',
 	'source/ecs/core.d',
@@ -9,14 +10,12 @@ src = [
 	'source/ecs/hash_map.d',
 	'source/ecs/id_manager.d',
 	'source/ecs/manager.d',
-	'source/ecs/simple_vector.d',
+	'source/ecs/package.d',
 	'source/ecs/simple_vector.d',
 	'source/ecs/std.d',
-	'source/ecs/atomic.d',
 	'source/ecs/system.d',
 	'source/ecs/traits.d',
-	'source/ecs/vector.d',
-	'source/ecs/package.d'
+	'source/ecs/vector.d'
 ]
 
 tests_src = [
diff --git a/source/ecs/manager.d b/source/ecs/manager.d
index f3c5db8..853cf14 100644
--- a/source/ecs/manager.d
+++ b/source/ecs/manager.d
@@ -164,14 +164,16 @@ export struct EntityManager
 
         foreach (ref system; systems)
         {
-            if (system.m_empty == true)
+            if (system.m_empty)
             {
-                addSystemCaller(system.id);
+                if (system.m_update)
+                    addSystemCaller(system.id);
                 continue;
             }
             if (system.m_update is null)
             {
-                if (system.m_add_entity || system.m_remove_entity || system.m_change_entity)
+                if (system.m_add_entity || system.m_remove_entity
+                        || system.m_change_entity || system.m_event_callers.length)
                 {
                     foreach (info; &entities_infos.byValue)
                     {
@@ -181,7 +183,7 @@ export struct EntityManager
                 continue;
             }
 
-            bool added = false;
+            /*bool added = false;
             foreach (i, caller; passes[system.m_pass].system_callers)
             {
                 if (systems[caller.system_id].priority > system.priority)
@@ -202,7 +204,8 @@ export struct EntityManager
                 sys_caller.job_group.caller = sys_caller;
                 system.m_any_system_caller = sys_caller;
                 passes[system.m_pass].system_callers.add(sys_caller);
-            }
+            }*/
+            addSystemCaller(system.id);
 
             foreach (info; &entities_infos.byValue)
             {
@@ -739,6 +742,9 @@ export struct EntityManager
             enum OnUpdateOverloadNum = -1;
         //enum HasOnUpdate = (hasMember!(Sys, "onUpdate") && checkOnUpdateParams());
 
+        static if (components_info.req.length == 0 && components_info.optional.length == 0)
+            system.m_empty = true;
+
         static if (OnUpdateOverloadNum != -1)
         {
             static if (components_info.req.length != 0 || components_info.optional.length != 0)
@@ -819,8 +825,6 @@ export struct EntityManager
                     (cast(typeof(&__traits(getOverloads, s,
                             "onUpdate")[OnUpdateOverloadNum])) data.update_delegate)(input_data);
                 }
-
-                system.m_empty = true;
             }
 
             system.m_update = &callUpdate;
@@ -1454,9 +1458,12 @@ export struct EntityManager
 
             foreach (i, ref system; systems)
             {
+                if (system.m_empty)
+                    continue;
                 if (system.m_update is null)
                 {
-                    if (system.m_add_entity || system.m_remove_entity || system.m_change_entity)
+                    if (system.m_add_entity || system.m_remove_entity
+                            || system.m_change_entity || system.m_event_callers.length)
                         connectListenerToEntityInfo(*info, cast(uint) i);
                     continue;
                 }
diff --git a/tests/tests.d b/tests/tests.d
index d75eb47..33ce587 100644
--- a/tests/tests.d
+++ b/tests/tests.d
@@ -412,6 +412,55 @@ struct Sys3
 	}
 }
 
+struct EmptyEventSystem
+{
+	mixin ECS.System;
+
+	bool handled = false;
+
+	struct EntitiesData
+	{
+		uint thread_id;
+	}
+
+	void handleEvent(Entity* entity, TestEvent event)
+	{
+		if(!handled)
+		{
+			printf("EmptyEventSystem.handleEvent() called!\n");
+			handled = true;
+		}
+		assert(0,"this shouldn't be called!");
+	}
+}
+
+struct EventSystem
+{
+	mixin ECS.System;
+	
+	bool handled = false;
+
+	struct EntitiesData
+	{
+		uint thread_id;
+		TestComp[] comp;
+	}
+
+	void handleEvent(Entity* entity, TestEvent event)
+	{
+		if(!handled)
+		{
+			printf("EventSystem.handleEvent() called!\n");
+			handled = true;
+		}
+	}
+
+	/*void onUpdate(EntitiesData)
+	{
+
+	}*/
+}
+
 struct EmptySystem
 {
 	mixin ECS.System;
@@ -458,7 +507,7 @@ struct TestSystem2
 		//TestComp* tt;
 	}
 
-	void handleEvent(Entity* entity, ref TestEvent event)
+	void handleEvent(Entity* entity, TestEvent event)
 	{
 		TestComp3* test = entity.getComponent!TestComp3;
 		test.bg = event.a;
@@ -467,7 +516,7 @@ struct TestSystem2
 		gEM.sendEvent(entity.id, event2);
 	}
 
-	void handleEvent(Entity* entity, ref TestEvent2 event)
+	void handleEvent(Entity* entity, TestEvent2 event)
 	{
 		TestComp3* test = entity.getComponent!TestComp3;
 		test.gg = cast(uint) event.a;
@@ -618,6 +667,8 @@ else:
 	gEM.registerSystem!Sys2(-100);
 	gEM.registerSystem!Sys3(-2);
 	gEM.registerSystem!EmptySystem(2);
+	gEM.registerSystem!EmptyEventSystem(2);
+	gEM.registerSystem!EventSystem(2);
 	//gEM.registerSystem!TestSystemWithHighPriority(100);
 	//gEM.registerSystem!TestSystem2(0);
 	gEM.endRegister();