diff --git a/src/doc/book/src/structs.md b/src/doc/book/src/structs.md
index 6b2a145c85e51..9f61e5b66289b 100644
--- a/src/doc/book/src/structs.md
+++ b/src/doc/book/src/structs.md
@@ -255,13 +255,14 @@ rather than positions.
 
 You can define a `struct` with no members at all:
 
-```rust
+```rust,compile_fail,E0423
 struct Electron {} // Use empty braces...
 struct Proton;     // ...or just a semicolon.
 
-// Whether you declared the struct with braces or not, do the same when creating one.
+// Use the same notation when creating an instance.
 let x = Electron {};
 let y = Proton;
+let z = Electron; // Error
 ```
 
 Such a `struct` is called ‘unit-like’ because it resembles the empty