diff --git a/Lib/test/test_fnmatch.py b/Lib/test/test_fnmatch.py
index 3a55b85..015c580 100644
--- a/Lib/test/test_fnmatch.py
+++ b/Lib/test/test_fnmatch.py
@@ -3,7 +3,7 @@
 from test import test_support
 import unittest
 
-from fnmatch import fnmatch, fnmatchcase
+from fnmatch import fnmatch, fnmatchcase, _MAXCACHE, _cache
 
 
 class FnmatchTestCase(unittest.TestCase):
@@ -49,6 +49,15 @@
         check('AbC', 'abc', 0, fnmatchcase)
         check('abc', 'AbC', 0, fnmatchcase)
 
+    def test_cache_clearing(self):
+        # check that caches do not grow too large
+        # http://bugs.python.org/issue7846
+
+        # string pattern cache
+        for i in range(_MAXCACHE + 1):
+            fnmatch('foo', '?' * i)
+
+        self.assertTrue(len(_cache) <= _MAXCACHE)
 
 def test_main():
     test_support.run_unittest(FnmatchTestCase)