diff --git a/wally/sensors/protocol.py b/wally/sensors/protocol.py
index c2ace01..7688f31 100644
--- a/wally/sensors/protocol.py
+++ b/wally/sensors/protocol.py
@@ -25,7 +25,12 @@
 
 class PickleSerializer(ISensortResultsSerializer):
     def pack(self, data):
-        ndata = {key: val.value for key, val in data.items()}
+        ndata = {}
+        for key, val in data.items():
+            if isinstance(val, basestring):
+                ndata[key] = val
+            else:
+                ndata[key] = val.value
         return pickle.dumps(ndata)
 
     def unpack(self, data):