Include tkinter.h only after including tk.h (or the equivalent for another platform).
diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 775598c..ea36297 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -33,8 +33,6 @@
 #include <windows.h>
 #endif
 
-#include "tkinter.h"
-
 /* Allow using this code in Python 2.[12] */
 #ifndef PyDoc_STRVAR
 #define PyDoc_STRVAR(name,str) static char name[] = str
@@ -69,6 +67,8 @@
 #include <tk.h>
 #endif
 
+#include "tkinter.h"
+
 /* For Tcl 8.2 and 8.3, CONST* is not defined (except on Cygwin). */
 #ifndef CONST84_RETURN
 #define CONST84_RETURN