diff --git a/src/conf.rs b/src/conf.rs
index e19a9b2..abf84ce 100644
--- a/src/conf.rs
+++ b/src/conf.rs
@@ -41,7 +41,7 @@ impl Conf {
 
         let s = Config::builder()
             .add_source(File::with_name("conf/default"))
-            .add_source(File::with_name(&format!("conf/{}", mode)).required(false))
+            .add_source(File::with_name(&format!("conf/{mode}")).required(false))
             .add_source(File::with_name("conf/secrets").required(false))
             .add_source(Environment::with_prefix("z2a"))
             .build()?;