Fix some Py_ssize_t issues
diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 0f6382e..ee9a633 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -932,12 +932,13 @@
 #ifdef Py_USING_UNICODE
 	else if (PyUnicode_Check(value)) {
 		Py_UNICODE *inbuf = PyUnicode_AS_UNICODE(value);
-		int size = PyUnicode_GET_SIZE(value);
+		Py_ssize_t size = PyUnicode_GET_SIZE(value);
 		/* This #ifdef assumes that Tcl uses UCS-2.
 		   See TCL_UTF_MAX test above. */
 #if defined(Py_UNICODE_WIDE) && TCL_UTF_MAX == 3
 		Tcl_UniChar *outbuf;
-		int i;
+		Py_ssize_t i;
+		assert(size < size * sizeof(Tcl_UniChar));
 		outbuf = (Tcl_UniChar*)ckalloc(size * sizeof(Tcl_UniChar));
 		if (!outbuf) {
 			PyErr_NoMemory();