diff --git a/pep-0454.txt b/pep-0454.txt
index a320f5452..8b056df00 100644
--- a/pep-0454.txt
+++ b/pep-0454.txt
@@ -62,6 +62,9 @@ environment variable (``PYTHONFAULTHANDLER`` and ``PYTHONTRACEMALLOC``),
 a ``-X`` command line option (``-X faulthandler`` and ``-X
 tracemalloc``).
 
+The tracemalloc module has been written for CPython. Other
+implementations of Python may not provide it.
+
 
 API
 ===