diff --git a/monasca_analytics/banana/bytecode/assembler.py b/monasca_analytics/banana/bytecode/assembler.py
index 5cbb5af..6d91325 100644
--- a/monasca_analytics/banana/bytecode/assembler.py
+++ b/monasca_analytics/banana/bytecode/assembler.py
@@ -497,7 +497,7 @@ class Code(object):
 
     stack_size = property(get_stack_size, set_stack_size)
 
-    def stackchange(self, (inputs, outputs)):
+    def stackchange(self, inputs, outputs):
         if self._ss is None:
             raise AssertionError("Unknown stack size at this location")
         self.stack_size -= inputs  # check underflow
diff --git a/monasca_analytics/banana/grammar/ast.py b/monasca_analytics/banana/grammar/ast.py
index efe3db9..8a54da7 100644
--- a/monasca_analytics/banana/grammar/ast.py
+++ b/monasca_analytics/banana/grammar/ast.py
@@ -561,7 +561,7 @@ class Connection(ASTNode):
 
     def __str__(self):
         res = "Connection<"
-        res += " {} ".format(map(lambda (x, y): (str(x), str(y)),
+        res += " {} ".format(map(lambda x, y: (str(x), str(y)),
                                  self.connections))
         res += ">"
         return res
diff --git a/test-requirements.txt b/test-requirements.txt
index 4ad317a..4b6a987 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,6 +1,6 @@
 # mock object framework
 coverage>=3.6 # Apache-2.0
 hacking>=0.10.2
-flake8>=2.5.4,<2.6.0 # MIT
+flake8>=2.5.4,<=3.5.0 # MIT
 nose==1.3.0
 mock>=1.0.1
diff --git a/tox.ini b/tox.ini
index ca97486..61999c3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -29,6 +29,7 @@ setenv = VIRTUAL_ENV={envdir}
          PYTHONPATH={homedir}/spark/spark-1.6.1/python:{homedir}/spark/spark-1.6.1/python/lib/py4j-0.9-src.zip:
 
 [testenv:pep8]
+basepython = python3
 commands =
     flake8 monasca_analytics test
 
@@ -41,7 +42,7 @@ install_command = pip install -U {opts} {packages}
 commands = {posargs}
 
 [flake8]
-ignore = F821,H201,H404,H405
+ignore = F821,H201,H404,H405,E305
 max-complexity = 50
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,tools,build