diff --git a/.travis.yml b/.travis.yml
index df43175c3..c90796313 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,9 @@
 language: python
-python: 2.7
+python: 3.5
 sudo: required
 dist: trusty
 env:
+  # XXX: There are too many tests failing on py2.7, so disable this for now.
   #matrix:
   #- TOX_ENV=py27
   #- TOX_ENV=py34
@@ -30,12 +31,13 @@ install:
   - travis_retry python setup.py install
   - travis_retry pip install -r dev_requirements.txt
 script:
-  # XXX: For now we're only performing minimal CI checks as most tests are
-  # broken. Tests will be individually added here as they're fixed.
+  # XXX: For now we're only performing minimal lint checks as there are way
+  # too many issues. Once they're all addressed we should change this to 'make
+  # lint'.
   - make lint-minimal
-  - make test-passing
+  - make test
   #- if [ -d .tox/$TOX_ENV/ ]; then cd .tox/$TOX_ENV && coverage erase; fi;
-  #- tox -e $TOX_ENV -- --ignore ethereum/tests/test_vm.py --ignore ethereum/tests/test_state.py
+  #- tox -e $TOX_ENV -- --ignore ethereum/tests/test_vm.py --ignore ethereum/tests/test_state.py --ignore ethereum/todo_tests
   #- tox -e $TOX_ENV -- ethereum/tests/test_vm.py
   #- tox -e $TOX_ENV -- ethereum/tests/test_state.py
   #- coverage report --show-missing
diff --git a/Makefile b/Makefile
index c1722ea76..21edb2a50 100644
--- a/Makefile
+++ b/Makefile
@@ -43,13 +43,10 @@ lint-minimal:
 	python -m flake8 --ignore=F401,F841,F811 --select=F --exclude=todo,experimental,ethash.py,ethash_utils.py ethereum
 
 test:
-	py.test --tb=no ethereum/tests/
+	py.test ethereum/tests/
 
-test-passing:
-	py.test ethereum/tests/test_abi.py ethereum/tests/test_bloom.py ethereum/tests/test_chain.py ethereum/tests/test_compress.py ethereum/tests/test_db.py ethereum/tests/test_difficulty.py ethereum/tests/test_opcodes.py ethereum/tests/test_trie_next_prev.py ethereum/tests/test_genesis.py ethereum/tests/test_serialization.py ethereum/tests/test_trie.py
-
-test-failing:
-	py.test ethereum/tests/test_blockstransactions.py ethereum/tests/test_transactions.py ethereum/tests/test_keys.py ethereum/tests/test_state.py ethereum/tests/test_contracts.py ethereum/tests/test_tester.py
+test-todo:
+	py.test --continue-on-collection-errors ethereum/todo_tests
 
 testnovm:
 	py.test --tb=no ethereum/tests/ --ignore=ethereum/tests/test_vm.py
diff --git a/ethereum/pow/chain.py b/ethereum/pow/chain.py
index 45f856e9c..64ec16913 100644
--- a/ethereum/pow/chain.py
+++ b/ethereum/pow/chain.py
@@ -372,7 +372,7 @@ def get_tx_position(self, tx):
     def get_transaction(self, tx):
         print('Deprecated. Use get_tx_position')
         blknum, index = self.get_tx_position(tx)
-        blk = self.get_block_by_number(blknum) 
+        blk = self.get_block_by_number(blknum)
         return blk.transactions[index], blk, index
 
     # Get descendants of a block
@@ -397,7 +397,7 @@ def get_blockhashes_from_hash(self, hash, max):
 
         header = block.header
         hashes = []
-        for i in xrange(max):
+        for i in range(max):
             hash = header.prevhash
             block = self.get_block(hash)
             if block is None:
diff --git a/ethereum/slogging.py b/ethereum/slogging.py
index 1b1c13986..455476d7c 100644
--- a/ethereum/slogging.py
+++ b/ethereum/slogging.py
@@ -1,5 +1,6 @@
 import logging
 import json
+import sys
 import textwrap
 from json.encoder import JSONEncoder
 from logging import StreamHandler, Formatter, FileHandler
@@ -256,11 +257,15 @@ def getLogger(self, name):
 
 
 def _stringify_dict_keys(input_):
+    if sys.version_info.major == 2:
+        longType = long # NOQA
+    else:
+        longType = int
     if isinstance(input_, dict):
         res = {}
         for k, v in input_.items():
             v = _stringify_dict_keys(v)
-            if not isinstance(k, (int, long, bool, None.__class__)):
+            if not isinstance(k, (int, longType, bool, None.__class__)):
                 k = str(k)
             res[k] = v
     elif isinstance(input_, (list, tuple)):
diff --git a/ethereum/utils.py b/ethereum/utils.py
index beb9b37f5..3df79b757 100644
--- a/ethereum/utils.py
+++ b/ethereum/utils.py
@@ -29,8 +29,8 @@
 SECP256K1P = 2**256 - 4294968273
 
 if sys.version_info.major == 2:
-    is_numeric = lambda x: isinstance(x, (int, long))
-    is_string = lambda x: isinstance(x, (str, unicode))
+    is_numeric = lambda x: isinstance(x, (int, long))  # NOQA
+    is_string = lambda x: isinstance(x, (str, unicode)) # NOQA
 
     def to_string(value):
         return str(value)
@@ -42,7 +42,7 @@ def int_to_bytes(value):
 
     def to_string_for_regexp(value):
         return str(value)
-    unicode = unicode
+    unicode = unicode # NOQA
 
     def bytearray_to_bytestr(value):
         return bytes(''.join(chr(c) for c in value))