diff --git a/src/doc/style-guide/src/expressions.md b/src/doc/style-guide/src/expressions.md
index 0aed8763a06..de8eba1dc6e 100644
--- a/src/doc/style-guide/src/expressions.md
+++ b/src/doc/style-guide/src/expressions.md
@@ -178,10 +178,12 @@ let f = Foo {
 Functional record update syntax is treated like a field, but it must never have
 a trailing comma. Do not put a space after `..`.
 
+```rust
 let f = Foo {
     field1,
     ..an_expr
 };
+```
 
 
 ### Tuple literals