Oops -- I introduced an off-by-6436159488 error.
diff --git a/Lib/test/test_zipfile64.py b/Lib/test/test_zipfile64.py
index b842cf2..de61ced 100644
--- a/Lib/test/test_zipfile64.py
+++ b/Lib/test/test_zipfile64.py
@@ -46,7 +46,7 @@
 
         # It will contain enough copies of self.data to reach about 6GB of
         # raw data to store.
-        filecount = 6*1024**2 // len(self.data)
+        filecount = 6*1024**3 // len(self.data)
 
         next_time = time.time() + _PRINT_WORKING_MSG_INTERVAL
         for num in range(filecount):