diff --git a/testcases/filtertestcase.py b/testcases/filtertestcase.py
index 7b18c4bf..8c706d58 100644
--- a/testcases/filtertestcase.py
+++ b/testcases/filtertestcase.py
@@ -234,6 +234,7 @@ class LogFile(unittest.TestCase):
 
 	def testIsModified(self):
 		self.assertTrue(self.filter.isModified(LogFile.FILENAME))
+		self.assertFalse(self.filter.isModified(LogFile.FILENAME))
 
 
 class LogFileMonitor(LogCaptureTestCase):