diff --git a/book/src/development/trait_checking.md b/book/src/development/trait_checking.md
index 6d01496eebe0..c6f6f6bd2f99 100644
--- a/book/src/development/trait_checking.md
+++ b/book/src/development/trait_checking.md
@@ -24,12 +24,11 @@ use rustc_span::symbol::sym;
 
 impl LateLintPass<'_> for CheckIteratorTraitLint {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
-		let implements_iterator = cx.tcx.get_diagnostic_item(sym::Iterator).map_or(false, |id| {
-    		implements_trait(cx, cx.typeck_results().expr_ty(expr), id, &[])
-		});
-		if implements_iterator {
-			// [...]
-		}
+        let implements_iterator = (cx.tcx.get_diagnostic_item(sym::Iterator))
+            .is_some_and(|id| implements_trait(cx, cx.typeck_results().expr_ty(expr), id, &[]));
+        if implements_iterator {
+            // [...]
+        }
 
     }
 }