diff --git a/flake.lock b/flake.lock
index 864f04c818..e30d593669 100644
--- a/flake.lock
+++ b/flake.lock
@@ -493,17 +493,17 @@
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1701336116,
-        "narHash": "sha256-kEmpezCR/FpITc6yMbAh4WrOCiT2zg5pSjnKrq51h5Y=",
+        "lastModified": 1694822471,
+        "narHash": "sha256-6fSDCj++lZVMZlyqOe9SIOL8tYSBz1bI8acwovRwoX8=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "f5c27c6136db4d76c30e533c20517df6864c46ee",
+        "rev": "47585496bcb13fb72e4a90daeea2f434e2501998",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixpkgs-unstable",
         "repo": "nixpkgs",
+        "rev": "47585496bcb13fb72e4a90daeea2f434e2501998",
         "type": "github"
       }
     },
diff --git a/flake.nix b/flake.nix
index 9a31ae57db..fd79439b3e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -10,7 +10,10 @@
     nixpkgs-2211 = { url = "github:NixOS/nixpkgs/nixpkgs-22.11-darwin"; };
     nixpkgs-2305 = { url = "github:NixOS/nixpkgs/nixpkgs-23.05-darwin"; };
     nixpkgs-2311 = { url = "github:NixOS/nixpkgs/nixpkgs-23.11-darwin"; };
-    nixpkgs-unstable = { url = "github:NixOS/nixpkgs/nixpkgs-unstable"; };
+    # The libsodium bump in 85c6e70b555fe892a049fa3d9dce000dc23a9562 breaks th-dll tests.
+    # And later it breaks in th-dll due to some change in the windows libs. We should probably
+    # drop unsable.
+    nixpkgs-unstable = { url = "github:NixOS/nixpkgs?rev=47585496bcb13fb72e4a90daeea2f434e2501998"; }; # nixpkgs-unstable };
     ghc98X = {
       flake = false;
       url = "git+https://gitlab.haskell.org/ghc/ghc?ref=ghc-9.8&submodules=1";