diff -r b49e366556ba Lib/test/test_tracemalloc.py
--- a/Lib/test/test_tracemalloc.py	Mon Jun 02 14:43:24 2014 +0200
+++ b/Lib/test/test_tracemalloc.py	Mon Jun 02 16:44:21 2014 +0300
@@ -3,6 +3,7 @@
 import sys
 import tracemalloc
 import unittest
+import io
 from unittest.mock import patch
 from test.script_helper import assert_python_ok, assert_python_failure
 from test import support
@@ -286,6 +287,13 @@
             exitcode = os.WEXITSTATUS(status)
             self.assertEqual(exitcode, 0)
 
+    def test_floating_point_error(self):
+        # This should not crash. The changeset 5b0fda8f5718 introduced
+        # a regression, which leads to a Floating point exception.
+        with io.BytesIO():
+            pass
+        with io.StringIO():
+            pass
 
 class TestSnapshot(unittest.TestCase):
     maxDiff = 4000
diff -r b49e366556ba Modules/_tracemalloc.c
--- a/Modules/_tracemalloc.c	Mon Jun 02 14:43:24 2014 +0200
+++ b/Modules/_tracemalloc.c	Mon Jun 02 16:44:21 2014 +0300
@@ -477,8 +477,9 @@
 {
     PyMemAllocator *alloc = (PyMemAllocator *)ctx;
     void *ptr;
-
-    assert(nelem <= PY_SIZE_MAX / elsize);
+    
+    if (elsize != 0)
+        assert(nelem <= PY_SIZE_MAX / elsize);
 
     if (use_calloc)
         ptr = alloc->calloc(alloc->ctx, nelem, elsize);