diff --git a/annotations/yo/stl/events.yo b/annotations/yo/stl/events.yo
index b5974bee..2d9dbf23 100644
--- a/annotations/yo/stl/events.yo
+++ b/annotations/yo/stl/events.yo
@@ -58,7 +58,7 @@ with objects of type tt(unique_lock<mutex>). This combination allows
 optimizations resulting in an increased efficiency compared to the efficiency
 that can be obtained with objects of the class
     hi(condition_variable_any)tt(std::condition_variable_any) that can be used
-with any (e.g., user-supplied) lock types.
+with any (e.g., user-supplied) lock type.
 
 The condition variable classes offer members like tt(wait, wait_for,
 wait_until, notify_one) and tt(notify_all) that may concurrently be called.