diff --git a/flake.lock b/flake.lock
index 5d3bfb046..cb1bf5400 100644
--- a/flake.lock
+++ b/flake.lock
@@ -49,11 +49,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1672485841,
-        "narHash": "sha256-4Ibn06cyIsV+jS7qjh0tIw670DJRbzCxhLuPJeC46o0=",
+        "lastModified": 1673257138,
+        "narHash": "sha256-UCJlNmIINOxga0OC+IkTpNPaat1kDuY2NB7+BjI0684=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "a73f033cc7e5e1c6ac8bbadbbe28e9625cf9ec47",
+        "rev": "d544b50ed3a98bb77288fbe227c5e1f66394f756",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 84190deb1..232c042a5 100644
--- a/flake.nix
+++ b/flake.nix
@@ -43,16 +43,8 @@
           '';
         };
 
-        hevm = pkgs.haskell.lib.dontCheck (
-          pkgs.haskellPackages.callCabal2nix "hevm" (pkgs.fetchFromGitHub {
-            owner = "ethereum";
-            repo = "hevm";
-            rev = "release/0.50.2";
-            sha256 = "sha256-RjGmlm+lbbzT9tC0s3KeqjRsN6BvX5K0M3/NpqaWNs8=";
-        }) { secp256k1 = pkgs.secp256k1; });
-
         echidna = with pkgs; lib.pipe
-          (haskellPackages.callCabal2nix "echidna" ./. { inherit hevm; })
+          (haskellPackages.callCabal2nix "echidna" ./. { })
           [
             (haskell.lib.compose.addTestToolDepends [ haskellPackages.hpack slither-analyzer solc ])
             (haskell.lib.compose.disableCabalFlag "static")
diff --git a/nix/pkgs.nix b/nix/pkgs.nix
deleted file mode 100644
index 01028e36c..000000000
--- a/nix/pkgs.nix
+++ /dev/null
@@ -1,5 +0,0 @@
-import (builtins.fetchTarball {
-  name = "nixpkgs-unstable-2022-01-07";
-  url = "https://github.com/nixos/nixpkgs/archive/d77bbfcbb650d9c219ca3286e1efb707b922d7c2.tar.gz";
-  sha256 = "sha256:1wh9qr6wvnfaprws2kbm4n9wxbckzh5d33lc4xfk6ama9bhbxr92";
-}) { }