diff --git a/quanttp/__main__.py b/quanttp/__main__.py
index c0fb48e..89fe540 100644
--- a/quanttp/__main__.py
+++ b/quanttp/__main__.py
@@ -58,6 +58,10 @@ def api_randnormal():
 def api_randbytes():
     try:
         length = int(request.args.get('length'))
+        if length < 1:
+            return Response('length must be greater than 0', status=400, content_type='text/plain')
+        elif length > 8192:
+            return Response('length must be less than or equal to 8192', status=400, content_type='text/plain')
         qng_wrapper.clear()
         return Response(qng_wrapper.randbytes(length), content_type='application/octet-stream')
     except ValueError as e:
@@ -85,6 +89,10 @@ def handle_ws_message(message, websocket, subscribed):
             websocket.send(str(qng_wrapper.randnormal()))
         elif split_message[0] == 'RANDBYTES':
             length = int(split_message[1])
+            if length < 1:
+                raise Exception('length must be greater than 0')
+            elif length > 8192:
+                raise Exception('length must be less than or equal to 8192')
             qng_wrapper.clear()
             websocket.send(qng_wrapper.randbytes(length))
         elif split_message[0] == 'SUBSCRIBEINT32':
@@ -107,6 +115,10 @@ def handle_ws_message(message, websocket, subscribed):
                     websocket.send(str(qng_wrapper.randnormal()))
         elif split_message[0] == 'SUBSCRIBEBYTES':
             chunk = int(split_message[1])
+            if chunk < 1:
+                raise Exception('chunk must be greater than 0')
+            elif chunk > 8192:
+                raise Exception('chunk must be less than or equal to 8192')
             qng_wrapper.clear()
             if not subscribed[0]:
                 subscribed[0] = True