diff --git a/lib/core/agent.py b/lib/core/agent.py
index cf1005c3c..59c361455 100644
--- a/lib/core/agent.py
+++ b/lib/core/agent.py
@@ -217,6 +217,9 @@ class Agent(object):
         if conf.direct:
             return self.payloadDirect(expression)
 
+        if expression is None:
+            return None
+
         expression = self.cleanupPayload(expression)
         expression = unescaper.escape(expression)
         query = None
@@ -258,6 +261,9 @@ class Agent(object):
         if conf.direct:
             return self.payloadDirect(expression)
 
+        if expression is None:
+            return None
+
         expression = self.cleanupPayload(expression)
 
         # Take default values if None