diff --git a/examples/pdm/example_lock.bzl b/examples/pdm/example_lock.bzl
index 21121975..70571375 100644
--- a/examples/pdm/example_lock.bzl
+++ b/examples/pdm/example_lock.bzl
@@ -1,3 +1,6 @@
+# This file is generated by rules_pycross.
+# It is not intended for manual editing.
+
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_file")
 load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
 load("@jvolkman_rules_pycross//pycross:defs.bzl", "pycross_wheel_build", "pycross_wheel_library", "pypi_file")
diff --git a/examples/poetry/example_lock.bzl b/examples/poetry/example_lock.bzl
index 2c70a7f8..7c9ae4b7 100755
--- a/examples/poetry/example_lock.bzl
+++ b/examples/poetry/example_lock.bzl
@@ -1,3 +1,6 @@
+# This file is generated by rules_pycross.
+# It is not intended for manual editing.
+
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_file")
 load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
 load("@jvolkman_rules_pycross//pycross:defs.bzl", "pycross_wheel_build", "pycross_wheel_library", "pypi_file")
diff --git a/pycross/private/tools/bzl_lock_generator.py b/pycross/private/tools/bzl_lock_generator.py
index 1f561f4b..ec002fc2 100644
--- a/pycross/private/tools/bzl_lock_generator.py
+++ b/pycross/private/tools/bzl_lock_generator.py
@@ -816,6 +816,9 @@ def w(*text):
 
         # Header stuff
         w(
+            '# This file is generated by rules_pycross.',
+            '# It is not intended for manual editing.',
+            '',
             'load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_file")',
             'load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")',
             'load("@jvolkman_rules_pycross//pycross:defs.bzl", "pycross_wheel_build", "pycross_wheel_library", "pypi_file")',