diff --git a/src/doc/rustc-dev-guide/src/conventions.md b/src/doc/rustc-dev-guide/src/conventions.md
index 93c5c44be796..d392ebd57222 100644
--- a/src/doc/rustc-dev-guide/src/conventions.md
+++ b/src/doc/rustc-dev-guide/src/conventions.md
@@ -69,7 +69,7 @@ for something that you want to get back to before you land your PR:
 ```rust,ignore
 fn do_something() {
     if something_else {
-        unimplemented!(): // TODO write this
+        unimplemented!(); // TODO write this
     }
 }
 ```