diff --git a/PC/python_nt.rc b/PC/python_nt.rc
index 91627637dac..3061deb7ab0 100644
--- a/PC/python_nt.rc
+++ b/PC/python_nt.rc
@@ -11,6 +11,7 @@
 /* Across releases, change:
  *    MS_DLL_ID if the minor version number changes.
  *    PYTHON_DLL_NAME ditto.
+ * MS_DLL_ID must match PY_VERSION in the Windows install script.
  */
 #define MS_DLL_ID "2.1"
 
diff --git a/PCbuild/python20.wse b/PCbuild/python20.wse
index f9bb5c4382f..cc9be9fb1ff 100644
--- a/PCbuild/python20.wse
+++ b/PCbuild/python20.wse
@@ -70,9 +70,12 @@ item: Set Variable
   Variable=GROUP
   Value=Python 2.1
 end
+item: Remark
+  Text=PY_VERSION should be major.minor only; used to create the registry key; must match MS_DLL_ID in python_nt.rc
+end
 item: Set Variable
   Variable=PY_VERSION
-  Value=2.1b1
+  Value=2.1
 end
 item: Set Variable
   Variable=MAINDIR