diff --git a/buildifier/buildifier_test-workspace.patch b/buildifier/buildifier_test-workspace.patch
deleted file mode 100644
index df21d48b1..000000000
--- a/buildifier/buildifier_test-workspace.patch
+++ /dev/null
@@ -1,37 +0,0 @@
-diff --git a/buildifier/internal/factory.bzl b/buildifier/internal/factory.bzl
-index bc317c6..8e1cc78 100644
---- a/buildifier/internal/factory.bzl
-+++ b/buildifier/internal/factory.bzl
-@@ -91,6 +91,7 @@ def buildifier_attr_factory(test_rule = False):
-                     ".sky",
-                     "BUILD",
-                     "WORKSPACE",
-+                    "WORKSPACE.bzlmod",
-                 ],
-                 doc = "A list of labels representing the starlark files to include in the test",
-             ),
-diff --git a/buildifier/runner.bash.template b/buildifier/runner.bash.template
-index 2ddbf3f..cc510fb 100644
---- a/buildifier/runner.bash.template
-+++ b/buildifier/runner.bash.template
-@@ -11,7 +11,7 @@ buildifier_short_path=$(readlink "$BUILDIFIER_SHORT_PATH")
- if [[ ! -z "${TEST_WORKSPACE+x}" && -z "${BUILD_WORKSPACE_DIRECTORY+x}" ]]; then
-   FIND_FILE_TYPE="l"
-   # If WORKSPACE was provided, then the script is being run under a test in no_sandbox mode
--  if [[ ! -z "${WORKSPACE+x}" ]]; then
-+  if [[ ! -z "${WORKSPACE:+x}" ]]; then
-     FIND_FILE_TYPE="f"
- 
-     # resolve the WORKSPACE symlink
-@@ -52,9 +52,11 @@ find . \
-     -o -name '*.BUILD' \
-     -o -name 'BUILD.*.bazel' \
-     -o -name 'BUILD.*.oss' \
-+    -o -name MODULE.bazel \
-     -o -name WORKSPACE \
-     -o -name WORKSPACE.bazel \
-     -o -name WORKSPACE.oss \
-+    -o -name WORKSPACE.bzlmod \
-     -o -name 'WORKSPACE.*.bazel' \
-     -o -name 'WORKSPACE.*.oss' \
-   \) -print | xargs "$buildifier_short_path" "${ARGS[@]}"
diff --git a/non_module_dev_deps.bzl b/non_module_dev_deps.bzl
index bca3a5a54..a7a1ad36d 100644
--- a/non_module_dev_deps.bzl
+++ b/non_module_dev_deps.bzl
@@ -66,12 +66,9 @@ def repositories(*, bzlmod):
     # no modules are provided at the moment for buildifier
     http_archive(
         name = "com_github_bazelbuild_buildtools",
-        sha256 = "42968f9134ba2c75c03bb271bd7bb062afb7da449f9b913c96e5be4ce890030a",
-        # fix runner.bash.template always returning success, format MODULE.bazel and WORKSPACE.bzlmod too
-        patches = ["@rules_haskell//buildifier:buildifier_test-workspace.patch"],
-        patch_args = ["-p1"],
-        strip_prefix = "buildtools-6.3.3",
-        urls = ["https://github.com/bazelbuild/buildtools/archive/v6.3.3.tar.gz"],
+        sha256 = "05c3c3602d25aeda1e9dbc91d3b66e624c1f9fdadf273e5480b489e744ca7269",
+        strip_prefix = "buildtools-6.4.0",
+        urls = ["https://github.com/bazelbuild/buildtools/archive/v6.4.0.tar.gz"],
     )
 
     nixpkgs_local_repository(
diff --git a/rules_haskell_nix/WORKSPACE.bzlmod b/rules_haskell_nix/WORKSPACE.bzlmod
index 8dbf72573..68a36f8e9 100644
--- a/rules_haskell_nix/WORKSPACE.bzlmod
+++ b/rules_haskell_nix/WORKSPACE.bzlmod
@@ -13,12 +13,9 @@ nixpkgs_package(
 
 http_archive(
     name = "com_github_bazelbuild_buildtools",
-    patch_args = ["-p1"],
-    # fix runner.bash.template always returning success, format MODULE.bazel and WORKSPACE.bzlmod too
-    patches = ["@rules_haskell//buildifier:buildifier_test-workspace.patch"],
-    sha256 = "42968f9134ba2c75c03bb271bd7bb062afb7da449f9b913c96e5be4ce890030a",
-    strip_prefix = "buildtools-6.3.3",
+    sha256 = "05c3c3602d25aeda1e9dbc91d3b66e624c1f9fdadf273e5480b489e744ca7269",
+    strip_prefix = "buildtools-6.4.0",
     urls = [
-        "https://github.com/bazelbuild/buildtools/archive/refs/tags/v6.3.3.tar.gz",
+        "https://github.com/bazelbuild/buildtools/archive/refs/tags/v6.4.0.tar.gz",
     ],
 )
diff --git a/rules_haskell_tests/non_module_deps.bzl b/rules_haskell_tests/non_module_deps.bzl
index e8be0c521..78696412f 100644
--- a/rules_haskell_tests/non_module_deps.bzl
+++ b/rules_haskell_tests/non_module_deps.bzl
@@ -65,12 +65,9 @@ def repositories(*, bzlmod):
     # no modules are provided at the moment for buildifier
     http_archive(
         name = "com_github_bazelbuild_buildtools",
-        sha256 = "42968f9134ba2c75c03bb271bd7bb062afb7da449f9b913c96e5be4ce890030a",
-        # fix runner.bash.template always returning success, format MODULE.bazel and WORKSPACE.bzlmod too
-        patches = ["@rules_haskell//buildifier:buildifier_test-workspace.patch"],
-        patch_args = ["-p1"],
-        strip_prefix = "buildtools-6.3.3",
-        urls = ["https://github.com/bazelbuild/buildtools/archive/v6.3.3.tar.gz"],
+        sha256 = "05c3c3602d25aeda1e9dbc91d3b66e624c1f9fdadf273e5480b489e744ca7269",
+        strip_prefix = "buildtools-6.4.0",
+        urls = ["https://github.com/bazelbuild/buildtools/archive/v6.4.0.tar.gz"],
     )
 
     http_archive(