diff --git a/source/chapter1/02_a_swift_tour.md b/source/chapter1/02_a_swift_tour.md
index b18a9e65..2ced756e 100755
--- a/source/chapter1/02_a_swift_tour.md
+++ b/source/chapter1/02_a_swift_tour.md
@@ -712,9 +712,9 @@ print(protocolValue.simpleDescription)
 
 ```swift
 enum PrinterError: Error {
-	case OutOfPaper
-	case NoToner
-	case OnFire
+	case outOfPaper
+	case noToner
+	case onFire
 }
 ```