diff --git a/Misc/NEWS b/Misc/NEWS
index 2a4b72223f2..5ea88f27901 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -907,6 +907,8 @@ Library
 Extension Modules
 -----------------
 
+- Bug #1301: Bad assert in _tkinter fixed.
+
 - Added bdist_wininst executable for VS 2008.
 
 - Bug #1604: collections.deque.__init__(iterable) now clears any prior contents
diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 3cef4e73a81..4308773419c 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -936,10 +936,12 @@ AsObj(PyObject *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;
+		Tcl_UniChar *outbuf = NULL;
 		Py_ssize_t i;
-		assert(size < size * sizeof(Tcl_UniChar));
-		outbuf = (Tcl_UniChar*)ckalloc(size * sizeof(Tcl_UniChar));
+		size_t allocsize = ((size_t)size) * sizeof(Tcl_UniChar);
+		if (allocsize >= size)
+			outbuf = (Tcl_UniChar*)ckalloc(allocsize);
+		/* Else overflow occurred, and we take the next exit */
 		if (!outbuf) {
 			PyErr_NoMemory();
 			return NULL;