diff -r 003f1f60a09c Modules/xxlimited.c
--- a/Modules/xxlimited.c	Sun Dec 27 12:24:06 2015 -0800
+++ b/Modules/xxlimited.c	Fri Jan 01 20:58:25 2016 +0000
@@ -10,7 +10,14 @@
    your own types of attributes instead.  Maybe you want to name your
    local variables other than 'self'.  If your object type is needed in
    other files, you'll have to create a file "foobarobject.h"; see
-   floatobject.h for an example. */
+   floatobject.h for an example.
+
+   This example uses the Py_LIMITED_API API.  See xxmodule.c for a version
+   that doesn't. */
+
+#ifndef Py_LIMITED_API
+# error "This file requires Py_LIMITED_API"
+#endif
 
 /* Xxo objects */
 
diff -r 003f1f60a09c Modules/xxmodule.c
--- a/Modules/xxmodule.c	Sun Dec 27 12:24:06 2015 -0800
+++ b/Modules/xxmodule.c	Fri Jan 01 20:58:25 2016 +0000
@@ -10,7 +10,10 @@
    your own types of attributes instead.  Maybe you want to name your
    local variables other than 'self'.  If your object type is needed in
    other files, you'll have to create a file "foobarobject.h"; see
-   floatobject.h for an example. */
+   floatobject.h for an example.
+
+   This example does not use the Py_LIMITED_API API.  See xxlimited.c for
+   a version that does. */
 
 /* Xxo objects */