diff --git a/temporalio/rbi/temporalio/workflow/future.rbi b/temporalio/rbi/temporalio/workflow/future.rbi
index e9f96348..875724dc 100644
--- a/temporalio/rbi/temporalio/workflow/future.rbi
+++ b/temporalio/rbi/temporalio/workflow/future.rbi
@@ -13,7 +13,7 @@ class Temporalio::Workflow::Future
   attr_reader :failure
 
   sig { params(block: T.nilable(T.proc.returns(Elem))).void }
-  def initialize(&); end
+  def initialize(&block); end
 
   sig { returns(T::Boolean) }
   def done?; end