diff --git a/readme.md b/readme.md
index c40fed8..a4d411b 100644
--- a/readme.md
+++ b/readme.md
@@ -343,16 +343,16 @@ const predicate = (a) => a > 2
 A contract specifies the obligations and guarantees of the behavior from a function or expression at runtime. This acts as a set of rules that are expected from the input and output of a function or expression, and errors are generally reported whenever a contract is violated.
 
 ```js
-// Define our contract : int -> int
+// Define our contract : int -> boolean
 const contract = (input) => {
   if (typeof input === 'number') return true
-  throw new Error('Contract violated: expected int -> int')
+  throw new Error('Contract violated: expected int -> boolean')
 }
 
 const addOne = (num) => contract(num) && num + 1
 
 addOne(2) // 3
-addOne('some string') // Contract violated: expected int -> int
+addOne('some string') // Contract violated: expected int -> boolean
 ```
 
 ## Category