diff --git a/flake.lock b/flake.lock
index 502ce4e..9d3e268 100644
--- a/flake.lock
+++ b/flake.lock
@@ -45939,6 +45939,22 @@
         "type": "github"
       }
     },
+    "nixpkgs_642": {
+      "locked": {
+        "lastModified": 1785366257,
+        "narHash": "sha256-pv+s8QHZNIncHBQ833zt9QZ+DeCb3mHk/1aDuX+xLNY=",
+        "owner": "danisharora099",
+        "repo": "nixpkgs",
+        "rev": "eaec81d3b8a8d2339e25c718a1650b2c45adf726",
+        "type": "github"
+      },
+      "original": {
+        "owner": "danisharora099",
+        "repo": "nixpkgs",
+        "rev": "eaec81d3b8a8d2339e25c718a1650b2c45adf726",
+        "type": "github"
+      }
+    },
     "nixpkgs_65": {
       "locked": {
         "lastModified": 1759036355,
@@ -47057,10 +47073,7 @@
         "logos-view-module-runtime": "logos-view-module-runtime_15",
         "nix-bundle-lgx": "nix-bundle-lgx_44",
         "nix-bundle-logos-module-install": "nix-bundle-logos-module-install_15",
-        "nixpkgs": [
-          "logos-nix",
-          "nixpkgs"
-        ],
+        "nixpkgs": "nixpkgs_642",
         "rust-overlay": "rust-overlay_5"
       }
     },
diff --git a/flake.nix b/flake.nix
index 65d3ec5..b8743ea 100644
--- a/flake.nix
+++ b/flake.nix
@@ -45,7 +45,15 @@
     logos-rust-sdk.inputs.logos-nix.follows = "logos-nix";
     logos-rust-sdk.inputs.logos-module-builder.follows = "logos-cpp-sdk";
     logos-rust-sdk.inputs.logos-logoscore-cli.follows = "logos-cpp-sdk";
-    nixpkgs.follows = "logos-nix/nixpkgs";
+    # HOTFIX (#159): crates.io now rejects the UA-less python fetch in this
+    # pin's fetchCargoVendor with HTTP 403, which breaks cargo vendoring in
+    # every module release that follows this flake's nixpkgs. This pin is the
+    # exact rev logos-nix locks (e9f00bd8) plus ONE commit: the upstream
+    # User-Agent fix (adapted from NixOS/nixpkgs@8209ba2b, NixOS/nixpkgs#512735),
+    # so the package set is byte-identical and all fixed-output hashes stay
+    # valid. Revert to `nixpkgs.follows = "logos-nix/nixpkgs"` once logos-nix
+    # advances past 2026-04-26 (first nixos-unstable containing the fix).
+    nixpkgs.url = "github:danisharora099/nixpkgs/eaec81d3b8a8d2339e25c718a1650b2c45adf726";
   };
 
   outputs = { self, nixpkgs, logos-cpp-sdk, logos-protocol, logos-qt-sdk, logos-module, logos-plugin-qt, logos-plugin-core, nix-bundle-logos-module-install, nix-bundle-lgx, logos-standalone-app, logos-test-framework, logos-rust-sdk, rust-overlay ? null, ... }: