diff --git a/Misc/SpecialBuilds.txt b/Misc/SpecialBuilds.txt
index 39dc1cb7c2b..feff20e5cd7 100644
--- a/Misc/SpecialBuilds.txt
+++ b/Misc/SpecialBuilds.txt
@@ -2,7 +2,8 @@ This file describes some special Python build types enabled via
 compile-time preprocessor defines.
 
 It is best to define these options in the OPT environment variable;
-``OPT="-DPy_REF_DEBUG" ./configure``.
+``OPT="-DPy_REF_DEBUG" ./configure``.  If you want the default values of
+OPT to also be included you will need to add them in yourself manually.
 
 ---------------------------------------------------------------------------
 Py_REF_DEBUG                                              introduced in 1.4