diff --git a/lib/core/agent.py b/lib/core/agent.py
index aa308914b..f200d8f75 100644
--- a/lib/core/agent.py
+++ b/lib/core/agent.py
@@ -241,7 +241,8 @@ class Agent(object):
             if not (expression and expression[0] == ';') and not (query and query[-1] in ('(', ')') and expression and expression[0] in ('(', ')')) and not (query and query[-1] == '('):
                 query += " "
 
-        query = "%s%s" % (query.replace('\\', BOUNDARY_BACKSLASH_MARKER), expression)
+        if query:
+            query = "%s%s" % (query.replace('\\', BOUNDARY_BACKSLASH_MARKER), expression)
 
         return query