diff --git a/pep-0437.txt b/pep-0437.txt
index f80a76fc1..c3eea0df9 100644
--- a/pep-0437.txt
+++ b/pep-0437.txt
@@ -113,6 +113,10 @@ above the converter function definition. The preprocessor will then catch
 any mismatch between the declarations.
 
 
+In order to keep the converter complexity manageable, PY_SSIZE_T_CLEAN will
+be deprecated and Py_ssize_t will be assumed for all length arguments.
+
+
 TBD: Make a list of fantasy types like *rw_buffer*.