diff --git a/concepts/rest-parameters/introduction.md b/concepts/rest-parameters/introduction.md
index 8e04c2d4..19410f4e 100644
--- a/concepts/rest-parameters/introduction.md
+++ b/concepts/rest-parameters/introduction.md
@@ -2,7 +2,7 @@
 
 In Common Lisp a function can have a parameter that will contain the "rest" of the arguments after any required or optional parameters are processed.
 This parameter is designated by the `&rest` lambda list keyword.
-If all arguments to a function are used by by other types of parameters then the rest parameter will be bound to an empty list.
+If all arguments to a function are used by other types of parameters then the rest parameter will be bound to an empty list.
 If there are unused arguments then the rest parameter will be bound to a list of those arguments.
 
 ```lisp