diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index d8e6041..04c2216 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -1,5 +1,6 @@
 # Python test set -- built-in functions
 
+import platform
 import test.test_support, unittest
 from test.test_support import fcmp, have_unicode, TESTFN, unlink, \
                               run_unittest, run_with_locale
@@ -1259,6 +1260,14 @@
         self.assertRaises(TypeError, round, t)
         self.assertRaises(TypeError, round, t, 0)
 
+    def test_round_large(self):
+        # Issue #1869: integral floats should remain unchanged
+        self.assertEqual(round(5e15-1), 5e15-1)
+        self.assertEqual(round(5e15), 5e15)
+        self.assertEqual(round(5e15+1), 5e15+1)
+        self.assertEqual(round(5e15+2), 5e15+2)
+        self.assertEqual(round(5e15+3), 5e15+3)
+
     def test_setattr(self):
         setattr(sys, 'spam', 1)
         self.assertEqual(sys.spam, 1)