diff --git a/build_pycompat.py b/build_pycompat.py
index 4ea3ecb..a5e79aa 100644
--- a/build_pycompat.py
+++ b/build_pycompat.py
@@ -189,6 +189,10 @@ def test_fuzzy_simple(i, s):
 
 # Here lies all the ugly junk.
 TEST_HEADER = '''
+//! This code has been generated by running the `build_pycompat.py` script
+//! in the repository root. Please do not edit it, as your edits will be destroyed
+//! upon re-running code generation.
+
 extern crate chrono;
 
 use chrono::Datelike;
diff --git a/build_pycompat_tokenizer.py b/build_pycompat_tokenizer.py
index ea0ed8c..0832618 100644
--- a/build_pycompat_tokenizer.py
+++ b/build_pycompat_tokenizer.py
@@ -24,6 +24,10 @@ fn test_tokenize{i}() {{
 
 
 TEST_HEADER = '''
+//! This code has been generated by running the `build_pycompat_tokenizer.py` script
+//! in the repository root. Please do not edit it, as your edits will be destroyed
+//! upon re-running code generation.
+
 use tokenize::Tokenizer;
 
 fn tokenize_assert(test_str: &str, comparison: Vec<&str>) {
diff --git a/src/tests/pycompat_parser.rs b/src/tests/pycompat_parser.rs
index 485bfa1..ca32d51 100644
--- a/src/tests/pycompat_parser.rs
+++ b/src/tests/pycompat_parser.rs
@@ -1,4 +1,8 @@
 
+//! This code has been generated by running the `build_pycompat.py` script
+//! in the repository root. Please do not edit it, as your edits will be destroyed
+//! upon re-running code generation.
+
 extern crate chrono;
 
 use chrono::Datelike;
diff --git a/src/tests/pycompat_tokenizer.rs b/src/tests/pycompat_tokenizer.rs
index fbf35c8..c2077d1 100644
--- a/src/tests/pycompat_tokenizer.rs
+++ b/src/tests/pycompat_tokenizer.rs
@@ -1,4 +1,8 @@
 
+//! This code has been generated by running the `build_pycompat_tokenizer.py` script
+//! in the repository root. Please do not edit it, as your edits will be destroyed
+//! upon re-running code generation.
+
 use tokenize::Tokenizer;
 
 fn tokenize_assert(test_str: &str, comparison: Vec<&str>) {