diff --git a/src/idioms/concat-format.md b/src/idioms/concat-format.md
index 8053a9c..462606f 100644
--- a/src/idioms/concat-format.md
+++ b/src/idioms/concat-format.md
@@ -18,7 +18,7 @@ fn say_hello(name: &str) -> String {
     // result
 
     // But using format! is better.
-    format!("Hello {}!", name)
+    format!("Hello {name}!")
 }
 ```