diff --git a/lightbug_http/middleware/basicauth.mojo b/lightbug_http/middleware/basicauth.mojo
index 8617c598..287046eb 100644
--- a/lightbug_http/middleware/basicauth.mojo
+++ b/lightbug_http/middleware/basicauth.mojo
@@ -10,7 +10,7 @@ struct BasicAuthMiddleware(Middleware):
     fn set_next(self, next: Middleware):
         self.next = next
 
-    fn __init__(self, username: String, password: String):
+    fn __init__(inout self, username: String, password: String):
         self.username = username
         self.password = password
 
diff --git a/lightbug_http/middleware/cors.mojo b/lightbug_http/middleware/cors.mojo
index cc4d60b9..67021e79 100644
--- a/lightbug_http/middleware/cors.mojo
+++ b/lightbug_http/middleware/cors.mojo
@@ -9,7 +9,7 @@ struct CorsMiddleware(Middleware):
     fn set_next(self, next: Middleware):
         self.next = next
 
-    fn __init__(self, allow_origin: String):
+    fn __init__(inout self, allow_origin: String):
         self.allow_origin = allow_origin
 
     fn call(self, context: Context) -> HTTPResponse:
diff --git a/lightbug_http/middleware/notfound.mojo b/lightbug_http/middleware/notfound.mojo
index 43719c48..1f6bf9b4 100644
--- a/lightbug_http/middleware/notfound.mojo
+++ b/lightbug_http/middleware/notfound.mojo
@@ -3,5 +3,10 @@ from lightbug_http.middleware.helpers import NotFound
 ## NotFound middleware returns a 404 response if no other middleware handles the request. It is a leaf node and always add at the end of the middleware chain
 @value
 struct NotFoundMiddleware(Middleware):
+    var next: Middleware
+    
+    fn set_next(self, next: Middleware):
+        self.next = next
+    
     fn call(self, context: Context) -> HTTPResponse:
         return NotFound("Not Found")
diff --git a/lightbug_http/middleware/router.mojo b/lightbug_http/middleware/router.mojo
index 8307c7b8..5aa7566c 100644
--- a/lightbug_http/middleware/router.mojo
+++ b/lightbug_http/middleware/router.mojo
@@ -17,7 +17,7 @@ struct RouterMiddleware[HTTPHandlerType: HTTPHandler](Middleware):
     fn set_next(self, next: Middleware):
         self.next = next
 
-    fn add(self, method: String, route: String, handler: HTTPHandler):
+    fn add(self, method: String, route: String, handler: HTTPHandlerType):
         self.routes[method + ":" + route] = handler
 
     fn call(self, context: Context) -> HTTPResponse:
diff --git a/lightbug_http/middleware/static.mojo b/lightbug_http/middleware/static.mojo
index 3634e388..d738e579 100644
--- a/lightbug_http/middleware/static.mojo
+++ b/lightbug_http/middleware/static.mojo
@@ -9,7 +9,7 @@ struct StaticMiddleware(Middleware):
     fn set_next(self, next: Middleware):
         self.next = next
 
-    fn __init__(self, path: String):
+    fn __init__(inout self, path: String):
         self.path = path
 
     fn call(self, context: Context) -> HTTPResponse:
@@ -19,7 +19,7 @@ struct StaticMiddleware(Middleware):
 
       try:
           var html: String
-          with open(file, "r") as f:
+          with open(path, "r") as f:
               html = f.read()
 
           return Success(html, "text/html")