diff --git a/mocha_server.py b/mocha_server.py
index 2e1dc9a..37363f6 100755
--- a/mocha_server.py
+++ b/mocha_server.py
@@ -31,6 +31,9 @@ def fetch_user(user_id):
     output = json.dumps([dict(row) for row in output])
     conn.close()
 
+    if output == '[]':
+        output = None
+
     return output
 
 
@@ -44,12 +47,11 @@ def process_request(uri):
     parts = uri.split('/')[1:]
     assert parts[0] == 'mocha'
 
-    output = ''
+    output = None
 
     if parts[1] == 'users':
         output = fetch_user(parts[2])
 
-
     return output