diff --git a/lambda-calculus.html.markdown b/lambda-calculus.html.markdown
index a5535d6c..53a7a7cd 100644
--- a/lambda-calculus.html.markdown
+++ b/lambda-calculus.html.markdown
@@ -85,7 +85,7 @@ Using `IF`, we can define the basic boolean logic operators:
 
 `a OR b` is equivalent to: `λab.IF a T b`
 
-`a NOT b` is equivalent to: `λa.IF a F T`
+`NOT a` is equivalent to: `λa.IF a F T`
 
 *Note: `IF a b c` is essentially saying: `IF((a b) c)`*