diff --git a/kafka/protocol/types.py b/kafka/protocol/types.py
index d508b2605..3dbd17413 100644
--- a/kafka/protocol/types.py
+++ b/kafka/protocol/types.py
@@ -181,9 +181,10 @@ def __init__(self, *array_of):
     def encode(self, items):
         if items is None:
             return Int32.encode(-1)
+        encoded_items = [self.array_of.encode(item) for item in items]
         return b''.join(
-            [Int32.encode(len(items))] +
-            [self.array_of.encode(item) for item in items]
+            [Int32.encode(len(encoded_items))] +
+            encoded_items
         )
 
     def decode(self, data):