diff --git a/.nix/config.nix b/.nix/config.nix
index 66d8826e9..3f86d6c0d 100644
--- a/.nix/config.nix
+++ b/.nix/config.nix
@@ -27,30 +27,24 @@ let master = [
   default-bundle = "coq-8.20";
   bundles = {
 
-    "coq-8.20" = {
-      coqPackages = common-bundles // {
-        coq.override.version = "8.20";
-      };
-      # only way to override elpi version is in .nix/coq-overlays/coq-elpi/default.nix
+    "coq-8.20".coqPackages = common-bundles // {
+      coq.override.version = "8.20";
+      coq-elpi.override.elpi-version = "2.0.7";
     };
 
-    "coq-master" = {
-      coqPackages = common-bundles // {
-        coq.override.version = "master";
-        stdlib.override.version = "master";
-        coqeal.job = false;  # broken in master, c.f. https://github.com/coq/coq/pull/19228
-      };
-      ocamlPackages = { elpi.override.version = "2.0.7"; };
+    "coq-master".coqPackages = common-bundles // {
+      coq.override.version = "master";
+      coq-elpi.override.elpi-version = "2.0.7";
+      stdlib.override.version = "master";
+      coqeal.job = false;  # broken in master, c.f. https://github.com/coq/coq/pull/19228
     };
       
     /* uncomment bundle below if min and max elpi version start to differ
-    "coq-master-min-elpi" = {
-      coqPackages = common-bundles // {
-        coq.override.version = "master";
-        stdlib.override.version = "master";
-        coqeal.job = false;  # broken in master, c.f. https://github.com/coq/coq/pull/19228
-      };
-      ocamlPackages = { elpi.override.version = "2.0.7"; };
+    "coq-master-min-elpi"coqPackages = common-bundles // {
+      coq.override.version = "master";
+      coq-elpi.override.elpi-version = "2.0.7";
+      stdlib.override.version = "master";
+      coqeal.job = false;  # broken in master, c.f. https://github.com/coq/coq/pull/19228
     }; */
 
   };
diff --git a/.nix/coq-nix-toolbox.nix b/.nix/coq-nix-toolbox.nix
index 12ed0a440..f367f82d1 100644
--- a/.nix/coq-nix-toolbox.nix
+++ b/.nix/coq-nix-toolbox.nix
@@ -1 +1 @@
-"a24e6f4fb01d4ca0811dc8d16246cfe36b37ac52"
+"82da08ded8f5b913ab813ab079a698eff6ab70e2"
diff --git a/.nix/coq-overlays/coq-elpi/default.nix b/.nix/coq-overlays/coq-elpi/default.nix
deleted file mode 100644
index 1658a4396..000000000
--- a/.nix/coq-overlays/coq-elpi/default.nix
+++ /dev/null
@@ -1,186 +0,0 @@
-{
-  lib,
-  mkCoqDerivation,
-  which,
-  coq,
-  stdlib,
-  version ? null,
-}:
-
-let
-  elpi = coq.ocamlPackages.elpi.override (
-    lib.switch coq.coq-version [
-      {
-        case = "8.11";
-        out = {
-          version = "1.11.4";
-        };
-      }
-      {
-        case = "8.12";
-        out = {
-          version = "1.12.0";
-        };
-      }
-      {
-        case = "8.13";
-        out = {
-          version = "1.13.7";
-        };
-      }
-      {
-        case = "8.14";
-        out = {
-          version = "1.13.7";
-        };
-      }
-      {
-        case = "8.15";
-        out = {
-          version = "1.15.0";
-        };
-      }
-      {
-        case = "8.16";
-        out = {
-          version = "1.17.0";
-        };
-      }
-      {
-        case = "8.17";
-        out = {
-          version = "1.17.0";
-        };
-      }
-      {
-        case = "8.18";
-        out = {
-          version = "1.18.1";
-        };
-      }
-      {
-        case = "8.19";
-        out = {
-          version = "1.18.1";
-        };
-      }
-      {
-        case = "8.20";
-        out = {
-          version = "2.0.7";
-        };
-      }
-    ] { version = "2.0.7"; }
-  );
-in
-(mkCoqDerivation {
-  pname = "elpi";
-  repo = "coq-elpi";
-  owner = "LPCIC";
-  inherit version;
-  defaultVersion = lib.switch coq.coq-version [
-    {
-      case = "8.20";
-      out = "2.2.0";
-    }
-    {
-      case = "8.19";
-      out = "2.0.1";
-    }
-    {
-      case = "8.18";
-      out = "2.0.0";
-    }
-    {
-      case = "8.17";
-      out = "1.18.0";
-    }
-    {
-      case = "8.16";
-      out = "1.15.6";
-    }
-    {
-      case = "8.15";
-      out = "1.14.0";
-    }
-    {
-      case = "8.14";
-      out = "1.11.2";
-    }
-    {
-      case = "8.13";
-      out = "1.11.1";
-    }
-    {
-      case = "8.12";
-      out = "1.8.3_8.12";
-    }
-    {
-      case = "8.11";
-      out = "1.6.3_8.11";
-    }
-  ] null;
-  release."2.2.0".sha256 = "sha256-rADEoqTXM7/TyYkUKsmCFfj6fjpWdnZEOK++5oLfC/I=";
-  release."2.0.1".sha256 = "sha256-cuoPsEJ+JRLVc9Golt2rJj4P7lKltTrrmQijjoViooc=";
-  release."2.0.0".sha256 = "sha256-A/cH324M21k3SZ7+YWXtaYEbu6dZQq3K0cb1RMKjbsM=";
-  release."1.19.0".sha256 = "sha256-kGoo61nJxeG/BqV+iQaV3iinwPStND+7+fYMxFkiKrQ=";
-  release."1.18.0".sha256 = "sha256-2fCOlhqi4YkiL5n8SYHuc3pLH+DArf9zuMH7IhpBc2Y=";
-  release."1.17.0".sha256 = "sha256-J8GatRKFU0ekNCG3V5dBI+FXypeHcLgC5QJYGYzFiEM=";
-  release."1.15.6".sha256 = "sha256-qc0q01tW8NVm83801HHOBHe/7H1/F2WGDbKO6nCXfno=";
-  release."1.15.1".sha256 = "sha256-NT2RlcIsFB9AvBhMxil4ZZIgx+KusMqDflj2HgQxsZg=";
-  release."1.14.0".sha256 = "sha256:1v2p5dlpviwzky2i14cj7gcgf8cr0j54bdm9fl5iz1ckx60j6nvp";
-  release."1.13.0".sha256 = "1j7s7dlnjbw222gnbrsjgmjck1yrx7h6hwm8zikcyxi0zys17w7n";
-  release."1.12.1".sha256 = "sha256-4mO6/co7NcIQSGIQJyoO8lNWXr6dqz+bIYPO/G0cPkY=";
-  release."1.11.2".sha256 = "0qk5cfh15y2zrja7267629dybd3irvxk1raz7z8qfir25a81ckd4";
-  release."1.11.1".sha256 = "10j076vc2hdcbm15m6s7b6xdzibgfcbzlkgjnlkr2vv9k13qf8kc";
-  release."1.10.1".sha256 = "1zsyx26dvj7pznfd2msl2w7zbw51q1nsdw0bdvdha6dga7ijf7xk";
-  release."1.9.7".sha256 = "0rvn12h9dpk9s4pxy32p8j0a1h7ib7kg98iv1cbrdg25y5vs85n1";
-  release."1.9.5".sha256 = "0gjdwmb6bvb5gh0a6ra48bz5fb3pr5kpxijb7a8mfydvar5i9qr6";
-  release."1.9.4".sha256 = "0nii7238mya74f9g6147qmpg6gv6ic9b54x5v85nb6q60d9jh0jq";
-  release."1.9.3".sha256 = "198irm800fx3n8n56vx1c6f626cizp1d7jfkrc6ba4iqhb62ma0z";
-  release."1.9.2".sha256 = "1rr2fr8vjkc0is7vh1461aidz2iwkigdkp6bqss4hhv0c3ijnn07";
-  release."1.8.3_8.12".sha256 = "15z2l4zy0qpw0ws7bvsmpmyv543aqghrfnl48nlwzn9q0v89p557";
-  release."1.8.3_8.12".version = "1.8.3";
-  release."1.8.2_8.12".sha256 = "1n6jwcdazvjgj8vsv2r9zgwpw5yqr5a1ndc2pwhmhqfl04b5dk4y";
-  release."1.8.2_8.12".version = "1.8.2";
-  release."1.8.1".sha256 = "1fbbdccdmr8g4wwpihzp4r2xacynjznf817lhijw6kqfav75zd0r";
-  release."1.8.0".sha256 = "13ywjg94zkbki22hx7s4gfm9rr87r4ghsgan23xyl3l9z8q0idd1";
-  release."1.7.0".sha256 = "1ws5cqr0xawv69prgygbl3q6dgglbaw0vc397h9flh90kxaqgyh8";
-  release."1.6.3_8.11".sha256 = "1j340cr2bv95clzzkkfmsjkklham1mj84cmiyprzwv20q89zr1hp";
-  release."1.6.3_8.11".version = "1.6.3";
-  release."1.6.2_8.11".sha256 = "06xrx0ljilwp63ik2sxxr7h617dgbch042xfcnfpy5x96br147rn";
-  release."1.6.2_8.11".version = "1.6.2";
-  release."1.6.1_8.11".sha256 = "0yyyh35i1nb3pg4hw7cak15kj4y6y9l84nwar9k1ifdsagh5zq53";
-  release."1.6.1_8.11".version = "1.6.1";
-  release."1.6.0_8.11".sha256 = "0ahxjnzmd7kl3gl38kyjqzkfgllncr2ybnw8bvgrc6iddgga7bpq";
-  release."1.6.0_8.11".version = "1.6.0";
-  release."1.6.0".sha256 = "0kf99i43mlf750fr7fric764mm495a53mg5kahnbp6zcjcxxrm0b";
-  releaseRev = v: "v${v}";
-
-  buildFlags = [ "OCAMLWARN=" ];
-
-  mlPlugin = true;
-  useDuneifVersion = v: lib.versions.isGe "2.2.0" v || v == "dev";
-  propagatedBuildInputs = [
-    coq.ocamlPackages.findlib
-    elpi
-    stdlib
-  ];
-
-  preConfigure = ''
-    make elpi/dune || true
-  '';
-
-  meta = {
-    description = "Coq plugin embedding ELPI";
-    maintainers = [ lib.maintainers.cohencyril ];
-    license = lib.licenses.lgpl21Plus;
-  };
-}).overrideAttrs
-  (
-    o:
-    lib.optionalAttrs (o.version != null && (o.version == "dev" || lib.versions.isGe "2.2.0" o.version))
-      {
-        propagatedBuildInputs = o.propagatedBuildInputs ++ [ coq.ocamlPackages.ppx_optcomp ];
-      }
-  )