diff --git a/nix/frama-ci.nix b/nix/frama-ci.nix
index ba8b10a47d5df6e03700e0cb3fcbaa6516329692..5e6a9b2212dd73d85b3bd49f040b52fc5371992e 100644
--- a/nix/frama-ci.nix
+++ b/nix/frama-ci.nix
@@ -5,8 +5,8 @@ let
     src = builtins.fetchGit {
             "url" = "https://bobot:${password}@git.frama-c.com/frama-c/Frama-CI.git";
             "name" = "Frama-CI";
-            "rev" = "4150f5b75b121450aef5687f779ec374ed7f1b92";
-            "ref" = "master";
+            "rev" = "bb2c9632abbb651363f2070d1cd89bc25cff5249";
+            "ref" = "fix/interface-files";
     };
     pkgs = import "${src}/pkgs.nix" {};
  in
diff --git a/nix/frama-ci.sh b/nix/frama-ci.sh
index dbbe1bb07e4976298cd85cb0a96675ab78d5ac56..b4deee0abc1543e01c82d3c6c92d9b0045b26d77 100755
--- a/nix/frama-ci.sh
+++ b/nix/frama-ci.sh
@@ -3,10 +3,10 @@
 DIR=$(dirname $0)
 
 export FRAMA_CI_NIX=$DIR/frama-ci.nix
-
 export FRAMA_CI=$(nix-instantiate --eval -E "((import <nixos-20.03> {}).callPackage $FRAMA_CI_NIX  { password = \"$TOKEN_FOR_API\";}).src.outPath")
 
 FRAMA_CI=${FRAMA_CI#\"}
 FRAMA_CI=${FRAMA_CI%\"}
 
+export NIX_PATH="nixpkgs=$(eval echo $(nix-instantiate --eval -E "with import $FRAMA_CI/pkgs-ref.nix; url"))"
 $FRAMA_CI/compile.sh $@