diff -rN -u old-1.8.2/src/allmydata/immutable/encode.py new-1.8.2/src/allmydata/immutable/encode.py
--- old-1.8.2/src/allmydata/immutable/encode.py	2011-06-21 11:54:33.015220996 -0600
+++ new-1.8.2/src/allmydata/immutable/encode.py	2011-06-21 11:54:33.187220996 -0600
@@ -105,6 +105,7 @@
         def _got_size(size):
             self.log(format="file size: %(size)d", size=size)
             self.file_size = size
+            precondition(isinstance(self.file_size, (int, long)), self.file_size)
         d.addCallback(_got_size)
         d.addCallback(lambda res: eu.get_all_encoding_parameters())
         d.addCallback(self._got_all_encoding_parameters)
@@ -118,6 +119,7 @@
     def _got_all_encoding_parameters(self, params):
         assert not self._codec
         k, happy, n, segsize = params
+        precondition(isinstance(segsize, (int, long)), segsize)
         self.required_shares = k
         self.servers_of_happiness = happy
         self.num_shares = n
@@ -129,6 +131,7 @@
 
         self.num_segments = mathutil.div_ceil(self.file_size,
                                               self.segment_size)
+        precondition(isinstance(self.num_segments, (int, long)), self.num_segments)
 
         self._codec = CRSEncoder()
         self._codec.set_params(self.segment_size,
diff -rN -u old-1.8.2/src/allmydata/immutable/upload.py new-1.8.2/src/allmydata/immutable/upload.py
--- old-1.8.2/src/allmydata/immutable/upload.py	2011-06-21 11:54:33.025220996 -0600
+++ new-1.8.2/src/allmydata/immutable/upload.py	2011-06-21 11:54:33.188220996 -0600
@@ -608,6 +608,7 @@
         d = self.original.get_all_encoding_parameters()
         def _got(encoding_parameters):
             (k, happy, n, segsize) = encoding_parameters
+            precondition(isinstance(segsize, (int, long)), segsize)
             self._segment_size = segsize # used by segment hashers
             self._encoding_parameters = encoding_parameters
             self.log("my encoding parameters: %s" % (encoding_parameters,),
@@ -915,6 +916,7 @@
         share_size = encoder.get_param("share_size")
         block_size = encoder.get_param("block_size")
         num_segments = encoder.get_param("num_segments")
+        precondition(isinstance(num_segments, (int, long)), num_segments)
         k,desired,n = encoder.get_param("share_counts")
 
         self._peer_selection_started = time.time()
@@ -1270,6 +1272,8 @@
         if self._all_encoding_parameters:
             return defer.succeed(self._all_encoding_parameters)
 
+        precondition(self.max_segment_size is None or isinstance(self.max_segment_size, (int, long)), self.max_segment_size)
+        precondition(isinstance(self.default_max_segment_size, (int, long)), self.default_max_segment_size)
         max_segsize = self.max_segment_size or self.default_max_segment_size
         k = self.encoding_param_k or self.default_encoding_param_k
         happy = self.encoding_param_happy or self.default_encoding_param_happy
@@ -1277,10 +1281,13 @@
 
         d = self.get_size()
         def _got_size(file_size):
+            precondition(isinstance(file_size, (int, long)), file_size)
             # for small files, shrink the segment size to avoid wasting space
             segsize = min(max_segsize, file_size)
+            precondition(isinstance(segsize, (int, long)), segsize)
             # this must be a multiple of 'required_shares'==k
             segsize = mathutil.next_multiple(segsize, k)
+            precondition(isinstance(segsize, (int, long)), segsize)
             encoding_parameters = (k, happy, n, segsize)
             self._all_encoding_parameters = encoding_parameters
             return encoding_parameters