diff --git a/docs/mkdocs/docs/features/arbitrary_types.md b/docs/mkdocs/docs/features/arbitrary_types.md
index a539ad815..fb7ab5d35 100644
--- a/docs/mkdocs/docs/features/arbitrary_types.md
+++ b/docs/mkdocs/docs/features/arbitrary_types.md
@@ -219,7 +219,7 @@ namespace nlohmann {
 
 ## Can I write my own serializer? (Advanced use)
 
-Yes. You might want to take a look at [`unit-udt.cpp`](https://github.com/nlohmann/json/blob/develop/test/src/unit-udt.cpp) in the test suite, to see a few examples.
+Yes. You might want to take a look at [`unit-udt.cpp`](https://github.com/nlohmann/json/blob/develop/tests/src/unit-udt.cpp) in the test suite, to see a few examples.
 
 If you write your own serializer, you'll need to do a few things: