diff --git a/lib/types.nix b/lib/types.nix
index 83f624e6b44..991fa0e5c29 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -261,7 +261,7 @@ rec {
     # declarations from the ‘options’ attribute of containing option
     # declaration.
     optionSet = mkOptionType {
-      name = /* builtins.trace "types.optionSet is deprecated; use types.submodule instead" */ "option set";
+      name = builtins.trace "types.optionSet is deprecated; use types.submodule instead" "option set";
     };
 
     # Augment the given type with an additional type check function.