diff --git a/doc/mkdocs/docs/features/arbitrary_types.md b/doc/mkdocs/docs/features/arbitrary_types.md
index 23913bba2..423419130 100644
--- a/doc/mkdocs/docs/features/arbitrary_types.md
+++ b/doc/mkdocs/docs/features/arbitrary_types.md
@@ -54,7 +54,7 @@ assert(p == p2);
 To make this work with one of your types, you only need to provide two functions:
 
 ```cpp
-using nlohmann::json;
+using json = nlohmann::json;
 
 namespace ns {
     void to_json(json& j, const person& p) {