diff --git a/nix/checks.ulu.nix b/nix/checks.ulu.nix
index c5829be..ecb0f6a 100644
--- a/nix/checks.ulu.nix
+++ b/nix/checks.ulu.nix
@@ -13,6 +13,8 @@
           nativeBuildInputs = old.nativeBuildInputs ++ tools;
           buildPhase = cmd;
           installPhase = "touch $out";
+          # The package patches its binary's RUNPATH; a check has no binary.
+          postFixup = "";
         });
     in
     {