diff --git a/nix/frama-ci.nix b/nix/frama-ci.nix
index 3976ce7088a3c25cb19a0f142a0452a3526cb14a..29658f8a20caae823d05b0a1c1f77bd67274b117 100644
--- a/nix/frama-ci.nix
+++ b/nix/frama-ci.nix
@@ -5,8 +5,8 @@ let
     src = builtins.fetchGit {
             "url" = "https://bobot:${password}@git.frama-c.com/frama-c/Frama-CI.git";
             "name" = "Frama-CI";
-            "rev" = "ed541f6e3818da2bf31125740b8555acb086ca29";
-            "ref" = "feature/andre/yojson-mandatory-dependence";
+            "rev" = "f7d5e96afa5b540feb4476b732e78dc8424bd10f";
+            "ref" = "feature/opam2";
     };
  in
  {
diff --git a/nix/frama-ci.sh b/nix/frama-ci.sh
index b4a69f90154968218273a70d50be6173a2909841..b331b057a8e8ec372a541e94d2af935a95b94f2a 100755
--- a/nix/frama-ci.sh
+++ b/nix/frama-ci.sh
@@ -4,7 +4,7 @@ DIR=$(dirname $0)
 
 export FRAMA_CI_NIX=$DIR/frama-ci.nix
 
-export FRAMA_CI=$(nix-instantiate --eval -E "((import <nixpkgs> {}).callPackage $FRAMA_CI_NIX  { password = \"$TOKEN_FOR_API\";}).src.outPath")
+export FRAMA_CI=$(nix-instantiate --eval -E "((import <nixos-19.03> {}).callPackage $FRAMA_CI_NIX  { password = \"$TOKEN_FOR_API\";}).src.outPath")
 
 FRAMA_CI=${FRAMA_CI#\"}
 FRAMA_CI=${FRAMA_CI%\"}