diff --git a/spec.md b/spec.md
index ede3ef0..0de1e82 100644
--- a/spec.md
+++ b/spec.md
@@ -179,7 +179,7 @@ function veryComplex(
 
 If one of the ORed conditions is `null`, it MUST be the last item in the list.
 
-An intersection of a single simple type with `null` SHOULD be abbreviated using the `?` alternate syntax: `?T`.
+A union of a single simple type with `null` SHOULD be abbreviated using the `?` alternate syntax: `?T`.
 
 ### 2.6 Trailing commas