diff --git a/lix/libutil/serialise.hh b/lix/libutil/serialise.hh
index 69230f6a2..74dfac0e6 100644
--- a/lix/libutil/serialise.hh
+++ b/lix/libutil/serialise.hh
@@ -598,10 +598,4 @@ struct FramedSink : nix::BufferedSink
     };
 };
 
-/* Disabling GC when entering a coroutine (without the boehm patch).
-   mutable to avoid boehm gc dependency in libutil.
- */
-extern std::shared_ptr<void> (*create_coro_gc_hook)();
-
-
 }