diff --git a/loopy/tools.py b/loopy/tools.py
index 524d2cf72512ce637ea2731a87b96f73f980dcff..56b673b597fc3bf43a6b03f87607ea8d3db0866a 100644
--- a/loopy/tools.py
+++ b/loopy/tools.py
@@ -396,12 +396,9 @@ class LazilyUnpicklingDictionary(collections.MutableMapping):
         return iter(self._map)
 
     def __getstate__(self):
-        return dict(
+        return {"_map": dict(
             (key, _PickledObjectWrapper.from_object(val))
-            for key, val in six.iteritems(self._map))
-
-    def __setstate__(self, state):
-        self._map = state
+            for key, val in six.iteritems(self._map))}
 
 # }}}
 
diff --git a/loopy/version.py b/loopy/version.py
index 35a86a995d34437c7a422547e1f9e202652a2498..2c15cc2dae6a1ef4b81a43a5b0025f1a0f16fc6a 100644
--- a/loopy/version.py
+++ b/loopy/version.py
@@ -32,4 +32,4 @@ except ImportError:
 else:
     _islpy_version = islpy.version.VERSION_TEXT
 
-DATA_MODEL_VERSION = "v57-islpy%s" % _islpy_version
+DATA_MODEL_VERSION = "v58-islpy%s" % _islpy_version
diff --git a/test/test_misc.py b/test/test_misc.py
index 139c337e16281900516b8e98c582918af043b958..a22e424630255df4225586eeb9f0d62a03d5318f 100644
--- a/test/test_misc.py
+++ b/test/test_misc.py
@@ -97,7 +97,7 @@ class PicklableItem(object):
     flags = {"unpickled": False}
 
     def __getstate__(self):
-        return ()
+        return True
 
     def __setstate__(self, state):
         PicklableItem.flags["unpickled"] = True
@@ -135,6 +135,14 @@ def test_LazilyUnpicklingDictionary():
 
     # }}}
 
+    # {{{ test empty map
+
+    mapping = LazilyUnpicklingDictionary({})
+    mapping = loads(dumps(mapping))
+    assert len(mapping) == 0
+
+    # }}}
+
 
 if __name__ == "__main__":
     if len(sys.argv) > 1: