diff --git a/scapy/packet.py b/scapy/packet.py
index 0ceadb3d253..f8a7772bcba 100644
--- a/scapy/packet.py
+++ b/scapy/packet.py
@@ -1151,6 +1151,8 @@ def is_valid_gen_tuple(x):
                     else:
                         len2 += 1
                 length *= len2 or 1
+            elif isinstance(val, types.GeneratorType):
+                length *= SetGen(val).__iterlen__()
         if not isinstance(self.payload, NoPayload):
             return length * self.payload.__iterlen__()
         return length