diff --git a/source/chapter2/21_Protocols.md b/source/chapter2/21_Protocols.md
index e1173fce..ea57a991 100755
--- a/source/chapter2/21_Protocols.md
+++ b/source/chapter2/21_Protocols.md
@@ -108,7 +108,7 @@ class Starship: FullyNamed {
 		self.prefix = prefix
 	}
 	var fullName: String {
-	return (prefix ? prefix ! + " " : " ") + name
+	return (prefix ? prefix! + " " : " ") + name
 	}
 }
 var ncc1701 = Starship(name: "Enterprise", prefix: "USS")