diff --git a/artiq-fast/fetchcargo.nix b/artiq-fast/fetchcargo.nix
index 6195a72..d50d0e1 100644
--- a/artiq-fast/fetchcargo.nix
+++ b/artiq-fast/fetchcargo.nix
@@ -3,6 +3,7 @@
 stdenv.mkDerivation {
   name = "${name}-vendor";
   nativeBuildInputs = [ cacert git cargo cargo-vendor ];
+  strictDeps = true;
   inherit src;
 
   phases = "unpackPhase patchPhase installPhase";