diff --git a/src/deferred_system.rs b/src/deferred_system.rs
index 0baf83d..c02e293 100644
--- a/src/deferred_system.rs
+++ b/src/deferred_system.rs
@@ -28,9 +28,9 @@ impl DeferredSystem {
 unsafe impl Send for DeferredSystem {}
 unsafe impl Sync for DeferredSystem {}
 
-pub fn new_deferred_system<S>(system: S, world: &mut World) -> (DeferredSystem, Arc<()>)
+pub fn new_deferred_system<S, M>(system: S, world: &mut World) -> (DeferredSystem, Arc<()>)
 where
-    S: IntoSystem<(), (), ()> + 'static,
+    S: IntoSystem<(), (), M> + 'static,
 {
     let id = world.register_system(system);
     let ref_count = Arc::new(());
diff --git a/src/hooks.rs b/src/hooks.rs
index dd88b78..a0e896a 100644
--- a/src/hooks.rs
+++ b/src/hooks.rs
@@ -38,9 +38,9 @@ where
     }
 }
 
-pub fn use_system<S>(cx: &ScopeState, system: S) -> DeferredSystem
+pub fn use_system<S, M>(cx: &ScopeState, system: S) -> DeferredSystem
 where
-    S: IntoSystem<(), (), ()> + 'static,
+    S: IntoSystem<(), (), M> + 'static,
 {
     cx.use_hook(|| new_deferred_system(system, EcsContext::get_world(cx)))
         .0