Restrict dill's upper bound.
diff --git a/sdks/python/setup.py b/sdks/python/setup.py
index 1c74f4f..7938113 100644
--- a/sdks/python/setup.py
+++ b/sdks/python/setup.py
@@ -105,7 +105,8 @@
'avro>=1.8.1,<2.0.0; python_version < "3.0"',
'avro-python3>=1.8.1,<2.0.0; python_version >= "3.0"',
'crcmod>=1.7,<2.0',
- 'dill>=0.2.9,<0.4.0',
+ # Dill doesn't guarantee comatibility between releases within minor version.
+ 'dill>=0.3.0,<0.3.1',
'fastavro>=0.21.4,<0.22',
'funcsigs>=1.0.2,<2; python_version < "3.0"',
'future>=0.16.0,<1.0.0',