Add #ifdefs so Tcl_Finalize isn't referenced when it's not defined.
diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index d1da535..8def1ef 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -1548,7 +1548,9 @@
 	if (PyErr_Occurred())
 		return;
 
+#if TKMAJORMINOR >= 8000
 	Py_AtExit(Tcl_Finalize);
+#endif
 
 #ifdef macintosh
 	/*