diff --git a/demos/03_demo.md b/demos/03_demo.md
index c93ba546dcace56d07b6f92aa169e84164cedf9e..0bf7da6ad8c7a77475d63ec388f8b86f43c855b2 100644
--- a/demos/03_demo.md
+++ b/demos/03_demo.md
@@ -1,4 +1,4 @@
-```ruby
+```swift
 func changeB(a:String, b: inout String) {
    b = "\(a)\(b)"
 }