diff --git a/pkgs/applications/audio/sonic-pi/default.nix b/pkgs/applications/audio/sonic-pi/default.nix
index 89ef9d848148..1d288f049b78 100644
--- a/pkgs/applications/audio/sonic-pi/default.nix
+++ b/pkgs/applications/audio/sonic-pi/default.nix
@@ -53,7 +53,7 @@ stdenv.mkDerivation rec {
     pname = "mix-deps-${pname}";
     mixEnv = "test";
     src = "${src}/app/server/beam/tau";
-    sha256 = "sha256-MvwUyVTS23vQKLpGxz46tEVCs/OyYk5dDaBlv+kYg1M=";
+    hash = "sha256-MvwUyVTS23vQKLpGxz46tEVCs/OyYk5dDaBlv+kYg1M=";
   };
 
   strictDeps = true;
diff --git a/pkgs/development/beam-modules/elixir-ls/default.nix b/pkgs/development/beam-modules/elixir-ls/default.nix
index 8573b4b7ca16..a4666f1520ab 100644
--- a/pkgs/development/beam-modules/elixir-ls/default.nix
+++ b/pkgs/development/beam-modules/elixir-ls/default.nix
@@ -21,7 +21,7 @@ mixRelease  {
   mixFodDeps = fetchMixDeps {
     pname = "mix-deps-${pname}";
     inherit src version elixir;
-    sha256 = "sha256-jF1Plkz1D85aWkiNgeBlJmHndhr7us+8+m/gMkXHvDw=";
+    hash = "sha256-jF1Plkz1D85aWkiNgeBlJmHndhr7us+8+m/gMkXHvDw=";
   };
 
   # elixir-ls is an umbrella app
diff --git a/pkgs/development/beam-modules/fetch-mix-deps.nix b/pkgs/development/beam-modules/fetch-mix-deps.nix
index 6d047dbe1ca5..b9a1add3c7d1 100644
--- a/pkgs/development/beam-modules/fetch-mix-deps.nix
+++ b/pkgs/development/beam-modules/fetch-mix-deps.nix
@@ -2,7 +2,8 @@
 
 { pname
 , version
-, sha256
+, hash ? ""
+, sha256 ? ""
 , src
 , mixEnv ? "prod"
 , debug ? false
@@ -13,6 +14,12 @@
 , ...
 }@attrs:
 
+let
+  hash_ =
+    if hash != "" then { outputHashAlgo = null; outputHash = hash; }
+    else if sha256 != "" then { outputHashAlgo = "sha256"; outputHash = sha256; }
+    else { outputHashAlgo = "sha256"; outputHash = lib.fakeSha256; };
+in
 stdenvNoCC.mkDerivation (attrs // {
   nativeBuildInputs = [ elixir hex cacert git ];
 
@@ -51,10 +58,8 @@ stdenvNoCC.mkDerivation (attrs // {
     runHook postInstall
   '';
 
-  outputHashAlgo = "sha256";
   outputHashMode = "recursive";
-  outputHash = sha256;
 
   impureEnvVars = lib.fetchers.proxyImpureEnvVars;
   inherit meta;
-})
+} // hash_)
diff --git a/pkgs/servers/web-apps/livebook/default.nix b/pkgs/servers/web-apps/livebook/default.nix
index 83f21cb474c6..44257acd56c9 100644
--- a/pkgs/servers/web-apps/livebook/default.nix
+++ b/pkgs/servers/web-apps/livebook/default.nix
@@ -19,7 +19,7 @@ beamPackages.mixRelease rec {
   mixFodDeps = beamPackages.fetchMixDeps {
     pname = "mix-deps-${pname}";
     inherit src version;
-    sha256 = "rwWGs4fGeuyV6BBFgCyyDwKf/YLgs1wY0xnHYy8iioE=";
+    hash = "sha256-rwWGs4fGeuyV6BBFgCyyDwKf/YLgs1wY0xnHYy8iioE=";
   };
 
   installPhase = ''
diff --git a/pkgs/servers/web-apps/plausible/default.nix b/pkgs/servers/web-apps/plausible/default.nix
index 43001649b07e..d890e571d97b 100644
--- a/pkgs/servers/web-apps/plausible/default.nix
+++ b/pkgs/servers/web-apps/plausible/default.nix
@@ -25,7 +25,7 @@ let
   mixFodDeps = beamPackages.fetchMixDeps {
     pname = "${pname}-deps";
     inherit src version;
-    sha256 = "1ikcskp4gvvdprl65x1spijdc8dz6klnrnkvgy2jbk0b3d7yn1v5";
+    hash = "sha256-ZQfrTxsLzCWFf3vabOk0vyHWZLw69GJovm3vR+7UbMY=";
   };
 
   yarnDeps = mkYarnModules {