diff --git a/pep-0665.rst b/pep-0665.rst
index 1e96839ae..1e67f6ebb 100644
--- a/pep-0665.rst
+++ b/pep-0665.rst
@@ -290,6 +290,10 @@ The timestamp for when the lock file was generated (using TOML's
 native timestamp type). It MUST be recorded using the UTC time zone to
 avoid ambiguity.
 
+If the SOURCE_DATE_EPOCH_ environment variable is set, it MUST be used
+as the timestamp by the locker. This faciliates reproducibility of the
+lock file itself.
+
 
 
 ``[tool]``
@@ -873,6 +877,7 @@ CC0-1.0-Universal license, whichever is more permissive.
 .. _SecureDrop: https://securedrop.org/
 .. _simple repository API: https://packaging.python.org/specifications/simple-repository-api/
 .. _source distribution file: https://packaging.python.org/specifications/source-distribution-format/
+.. _SOURCE_DATE_EPOCH: https://reproducible-builds.org/specs/source-date-epoch/
 .. _TOML: https://toml.io
 .. _version specifiers spec: https://packaging.python.org/specifications/version-specifiers/
 .. _wheel file: https://packaging.python.org/specifications/binary-distribution-format/