diff --git a/nixpkgs/nixos-unstable.nix b/nixpkgs/nixos-unstable.nix
new file mode 100644
index 000000000..4b3e23af6
--- /dev/null
+++ b/nixpkgs/nixos-unstable.nix
@@ -0,0 +1,10 @@
+{ ... }@args:
+let
+  # 2024-04-27
+  sha256 = "sha256:1iy5vigbw2dx7rhzmsszc7d87sw545f0vw4kcwxk3mazxg9qrzgl";
+  rev = "2b1f64b358f2cab62617f26b3870fd0ee375d848";
+in
+import (fetchTarball {
+  inherit sha256;
+  url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
+}) args
diff --git a/rules_haskell_tests/MODULE.bazel b/rules_haskell_tests/MODULE.bazel
index a822b4324..22fd99523 100644
--- a/rules_haskell_tests/MODULE.bazel
+++ b/rules_haskell_tests/MODULE.bazel
@@ -126,6 +126,7 @@ use_repo(
     "nixpkgs_go_sdk_toolchains",
     "nixpkgs_lz4",
     "nixpkgs_python_toolchain",
+    "nixpkgs_unstable",
     "toolchains_libraries",
     "zlib.dev",
 )
diff --git a/rules_haskell_tests/non_module_deps_1.bzl b/rules_haskell_tests/non_module_deps_1.bzl
index 43e63ee3e..8ae5158fb 100644
--- a/rules_haskell_tests/non_module_deps_1.bzl
+++ b/rules_haskell_tests/non_module_deps_1.bzl
@@ -58,6 +58,12 @@ def repositories(*, bzlmod):
         nix_file = "//nixpkgs:default.nix",
     )
 
+    # TODO switch back to nixpkgs_default once bazel_* matches the version in .bazelversion
+    nixpkgs_local_repository(
+        name = "nixpkgs_unstable",
+        nix_file = "//nixpkgs:nixos-unstable.nix",
+    )
+
     nixpkgs_package(
         name = "glibc_locales",
         attribute_path = "glibcLocales",
diff --git a/rules_haskell_tests/tests/integration_testing/dependencies.bzl b/rules_haskell_tests/tests/integration_testing/dependencies.bzl
index c94bbd7f3..b4b18af0b 100644
--- a/rules_haskell_tests/tests/integration_testing/dependencies.bzl
+++ b/rules_haskell_tests/tests/integration_testing/dependencies.bzl
@@ -11,7 +11,8 @@ def integration_testing_bazel_binaries():
     for package in SUPPORTED_NIXPKGS_BAZEL_PACKAGES:
         nixpkgs_package(
             name = package,
-            repository = "@nixpkgs_default",
+            # TODO switch back to nixpkgs_default once bazel_* matches the version in .bazelversion
+            repository = "@nixpkgs_unstable",
             build_file_content = """\
 filegroup(
     name = "bazel_bin",
diff --git a/shell.nix b/shell.nix
index 38a21a923..f6db1c936 100644
--- a/shell.nix
+++ b/shell.nix
@@ -3,6 +3,8 @@
 with pkgs;
 
 let
+  nixos-unstable = import ./nixpkgs/nixos-unstable.nix { };
+
   macOS-security =
     # make `/usr/bin/security` available in `PATH`, which is needed for stack
     # on darwin which calls this binary to find certificates
@@ -42,7 +44,8 @@ mkShell {
   ++ lib.optionals docTools [ graphviz python39Packages.sphinx zip unzip ]
   ++ lib.optional stdenv.isDarwin macOS-security;
 
-  packages = [ bazel_6 ];
+  # TODO switch back to default nixpkgs once bazel_* matches the version in .bazelversion
+  packages = [ nixos-unstable.bazel_6 ];
 
   shellHook = ''
     # Add nix config flags to .bazelrc.local.