diff --git a/src/kemal/dsl.cr b/src/kemal/dsl.cr
index 9ede832..6b5d589 100644
--- a/src/kemal/dsl.cr
+++ b/src/kemal/dsl.cr
@@ -1,7 +1,7 @@
 HTTP_METHODS = %w(get post put patch delete options)
 
 {% for method in HTTP_METHODS %}
-  def {{method.id}}(path, &block : HTTP::Server::Context -> String)
+  def {{method.id}}(path, &block : HTTP::Server::Context -> _)
    Kemal::RouteHandler::INSTANCE.add_route({{method}}.upcase, path, &block)
   end
 {% end %}
diff --git a/src/kemal/route.cr b/src/kemal/route.cr
index 38b9668..fc184c5 100644
--- a/src/kemal/route.cr
+++ b/src/kemal/route.cr
@@ -6,7 +6,7 @@ class Kemal::Route
   @handler : HTTP::Server::Context -> String
   @method : String
 
-  def initialize(@method, @path : String, &handler )
+  def initialize(@method, @path : String, &handler : HTTP::Server::Context -> _)
     @handler = ->(context : HTTP::Server::Context){ handler.call(context).to_s }
   end
 end
diff --git a/src/kemal/route_handler.cr b/src/kemal/route_handler.cr
index 5ced2e2..a3278d5 100644
--- a/src/kemal/route_handler.cr
+++ b/src/kemal/route_handler.cr
@@ -19,7 +19,7 @@ class Kemal::RouteHandler < HTTP::Handler
 
   # Adds a given route to routing tree. As an exception each `GET` route additionaly defines
   # a corresponding `HEAD` route.
-  def add_route(method, path, &handler : HTTP::Server::Context -> String)
+  def add_route(method, path, &handler : HTTP::Server::Context -> _)
     add_to_radix_tree method, path, Route.new(method, path, &handler)
     add_to_radix_tree("HEAD", path, Route.new("HEAD", path, &handler)) if method == "GET"
   end