diff --git a/taskflow/persistence/backends/impl_memory.py b/taskflow/persistence/backends/impl_memory.py
index e614247d..960ebe0c 100644
--- a/taskflow/persistence/backends/impl_memory.py
+++ b/taskflow/persistence/backends/impl_memory.py
@@ -75,6 +75,9 @@ class FakeFilesystem(object):
     @classmethod
     def normpath(cls, path):
         """Return a normalized absolutized version of the pathname path."""
+        if not path:
+            raise ValueError("This filesystem can only normalize paths"
+                             " that are not empty")
         if not path.startswith(cls.root_path):
             raise ValueError("This filesystem can only normalize"
                              " paths that start with %s: '%s' is not"
diff --git a/taskflow/tests/unit/persistence/test_memory_persistence.py b/taskflow/tests/unit/persistence/test_memory_persistence.py
index 2b3599e4..24f76aa3 100644
--- a/taskflow/tests/unit/persistence/test_memory_persistence.py
+++ b/taskflow/tests/unit/persistence/test_memory_persistence.py
@@ -128,6 +128,12 @@ class MemoryFilesystemTest(test.TestCase):
         fs = impl_memory.FakeFilesystem()
         self.assertRaises(exc.NotFound, self._get_item_path, fs, '/c')
 
+    def test_bad_norms(self):
+        fs = impl_memory.FakeFilesystem()
+        self.assertRaises(ValueError, fs.normpath, '')
+        self.assertRaises(ValueError, fs.normpath, 'abc/c')
+        self.assertRaises(ValueError, fs.normpath, '../c')
+
     def test_del_root_not_allowed(self):
         fs = impl_memory.FakeFilesystem()
         self.assertRaises(ValueError, self._del_item_path, fs, '/')