diff --git a/pkgs/development/libraries/eigen/default.nix b/pkgs/development/libraries/eigen/default.nix
index e612add0c7b1e0..8fe840bea596df 100644
--- a/pkgs/development/libraries/eigen/default.nix
+++ b/pkgs/development/libraries/eigen/default.nix
@@ -2,37 +2,22 @@
   lib,
   stdenv,
   fetchFromGitLab,
-  fetchpatch,
   cmake,
 }:
 
 stdenv.mkDerivation rec {
   pname = "eigen";
-  version = "3.4.0";
+  version = "3.4.0-unstable-2022-05-19";
 
   src = fetchFromGitLab {
     owner = "libeigen";
-    repo = pname;
-    rev = version;
-    hash = "sha256-1/4xMetKMDOgZgzz3WMxfHUEpmdAm52RqZvz6i0mLEw=";
+    repo = "eigen";
+    rev = "e7248b26a1ed53fa030c5c459f7ea095dfd276ac";
+    hash = "sha256-uQ1YYV3ojbMVfHdqjXRyUymRPjJZV3WHT36PTxPRius=";
   };
 
   patches = [
     ./include-dir.patch
-
-    # Fixes e.g. onnxruntime on aarch64-darwin:
-    # https://hydra.nixos.org/build/248915128/nixlog/1,
-    # originally suggested in https://github.com/NixOS/nixpkgs/pull/258392.
-    #
-    # The patch is from
-    # ["Fix vectorized reductions for Eigen::half"](https://gitlab.com/libeigen/eigen/-/merge_requests/699)
-    # which is two years old,
-    # but Eigen hasn't had a release in two years either:
-    # https://gitlab.com/libeigen/eigen/-/issues/2699.
-    (fetchpatch {
-      url = "https://gitlab.com/libeigen/eigen/-/commit/d0e3791b1a0e2db9edd5f1d1befdb2ac5a40efe0.patch";
-      hash = "sha256-8qiNpuYehnoiGiqy0c3Mcb45pwrmc6W4rzCxoLDSvj0=";
-    })
   ];
 
   nativeBuildInputs = [ cmake ];