diff --git a/lib/oga/xpath/evaluator.rb b/lib/oga/xpath/evaluator.rb
index a51a14c..197b566 100644
--- a/lib/oga/xpath/evaluator.rb
+++ b/lib/oga/xpath/evaluator.rb
@@ -1188,7 +1188,7 @@ module Oga
       # This function call returns the substring of the 1st argument that occurs
       # after the string given in the 2nd argument. For example:
       #
-      #     substring-before("2014-08-25", "-")
+      #     substring-after("2014-08-25", "-")
       #
       # This would return "08-25" as it occurs after the first "-".
       #