diff --git a/doc/docs.md b/doc/docs.md
index 7edd93b3a48cf6..bfc754b9dd93f0 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -6191,6 +6191,8 @@ To improve safety and maintainability, operator overloading is limited.
 
 - When overriding `<` and `==`, the return type must be strictly `bool`.
 - Both arguments must have the same type (just like with all operators in V).
+- Overloaded operators have to return the same type as the argument
+  (the exceptions are `<` and `==`).
 
 #### Other restrictions