diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
index bbdfeb0b3f9..f102fa7f0ca 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
@@ -5662,7 +5662,7 @@ The package provides two traits-class decorators, namely
 debugging and informative metadata to an output stream. The former is
 used to count the number of invocations of traits-class functors, and
 the latter is used to trace these invocations. Note that the
-constructors of each of these class templates applies perfect
+constructors of each of these class templates apply perfect
 forwarding. The counting traits also exports the count of traits-class
 objects of specific types constructed during the execution of the
 program. The tracing traits supports filtering of traced functors. The