diff --git a/src/allmydata/download.py b/src/allmydata/download.py
index 5051a1e4e..ef855d159 100644
--- a/src/allmydata/download.py
+++ b/src/allmydata/download.py
@@ -127,7 +127,8 @@ class FileDownloader:
 
         d.addCallback(lambda res: self._decoder.decode(shares))
 
-        def _write(data):
+        def _write(decoded_shares):
+            data = "".join(decoded_shares)
             self._target.open()
             hasher = sha.new(netstring("allmydata_v1_verifierid"))
             hasher.update(data)
diff --git a/src/allmydata/test/test_codec.py b/src/allmydata/test/test_codec.py
index d073ae8c1..f7e84cefa 100644
--- a/src/allmydata/test/test_codec.py
+++ b/src/allmydata/test/test_codec.py
@@ -34,7 +34,8 @@ class Tester:
             d1 = dec.decode(shares)
             return d1
 
-        def _check_data(data1):
+        def _check_data(decoded_shares):
+            data1 = "".join(decoded_shares)
             self.failUnlessEqual(len(data1), len(data0))
             self.failUnless(data1 == data0)