diff --git a/source/ecs/manager.d b/source/ecs/manager.d
index 26ffb5a..92f4aaf 100644
--- a/source/ecs/manager.d
+++ b/source/ecs/manager.d
@@ -304,7 +304,7 @@ class EntityManager
                     else
                     { 
                         enum long indexInEntitiesData=getIndexOfTypeInEntitiesData!(Sys.EntitiesData, EventFieldType);
-                        static assert(indexInEntitiesData != -1);// Type present in EventInput has to be present in EntitiesData
+                        static assert(indexInEntitiesData != -1, "Component present in EventInput has to be present in EntitiesData!");// Type present in EventInput has to be present in EntitiesData
 
                         enum bool isOptional = hasUDA!(Sys.EntitiesData.tupleof[indexInEntitiesData], "optional");
                         static if(isOptional)