diff --git a/STL_Extension/doc/STL_Extension/Concepts/SurjectiveLockDataStructure.h b/STL_Extension/doc/STL_Extension/Concepts/SurjectiveLockDataStructure.h
index 766c25fd0d0..68bc8240d84 100644
--- a/STL_Extension/doc/STL_Extension/Concepts/SurjectiveLockDataStructure.h
+++ b/STL_Extension/doc/STL_Extension/Concepts/SurjectiveLockDataStructure.h
@@ -14,7 +14,7 @@ another point in the same voxel has been locked.
 The only requirement is that when a thread owns the lock of an object, no other
 thread can lock the same object.
 
-We call `S` the surjective function such as `S(object)`
+We call `S` the surjective function such that `S(object)`
 is the \"thing\" that is locked when one tries to lock `object`. 
 In the previous example, `S(point)` is the voxel containing `point`.