diff --git a/module_build_service/builder/KojiContentGenerator.py b/module_build_service/builder/KojiContentGenerator.py
index 5c4bbe00..bb39672b 100644
--- a/module_build_service/builder/KojiContentGenerator.py
+++ b/module_build_service/builder/KojiContentGenerator.py
@@ -33,6 +33,8 @@ import shutil
 import subprocess
 import tempfile
 import time
+from builtins import str
+from io import open
 
 import koji
 
@@ -145,21 +147,16 @@ class KojiContentGenerator(object):
         sep = ';'
         fmt = sep.join(["%%{%s}" % tag for tag in tags])
         cmd = "/bin/rpm -qa --qf '{0}\n'".format(fmt)
-        try:
-            # py3
-            (status, output) = subprocess.getstatusoutput(cmd)
-        except AttributeError:
-            # py2
-            with open('/dev/null', 'r+') as devnull:
-                p = subprocess.Popen(cmd,
-                                     shell=True,
-                                     stdin=devnull,
-                                     stdout=subprocess.PIPE,
-                                     stderr=devnull)
+        with open('/dev/null', 'r+') as devnull:
+            p = subprocess.Popen(cmd,
+                                 shell=True,
+                                 stdin=devnull,
+                                 stdout=subprocess.PIPE,
+                                 stderr=devnull)
 
-                (stdout, stderr) = p.communicate()
-                status = p.wait()
-                output = stdout.decode()
+            (stdout, stderr) = p.communicate()
+            status = p.wait()
+            output = stdout
 
         if status != 0:
             log.debug("%s: stderr output: %s", cmd, stderr)
@@ -173,7 +170,7 @@ class KojiContentGenerator(object):
         tools = [u"modulemd"]
         ret = []
         for tool in tools:
-            version = unicode(pkg_resources.get_distribution(tool).version)
+            version = str(pkg_resources.get_distribution(tool).version)
             ret.append({u"name": tool,
                         u"version": version})
         return ret
@@ -236,15 +233,15 @@ class KojiContentGenerator(object):
         ret = {
             u"id": 1,
             u"host": {
-                u"arch": unicode(platform.machine()),
+                u"arch": str(platform.machine()),
                 u'os': u"%s %s" % (distro[0], distro[1])
             },
             u"content_generator": {
                 u"name": u"module-build-service",
-                u"version": unicode(version)
+                u"version": str(version)
             },
             u"container": {
-                u"arch": unicode(platform.machine()),
+                u"arch": str(platform.machine()),
                 u"type": u"none"
             },
             u"components": self.__get_rpms(),
@@ -281,7 +278,7 @@ class KojiContentGenerator(object):
                 },
                 u'filesize': len(self.mmd),
                 u'checksum_type': u'md5',
-                u'checksum': unicode(hashlib.md5(self.mmd).hexdigest()),
+                u'checksum': str(hashlib.md5(self.mmd.encode('utf-8')).hexdigest()),
                 u'filename': u'modulemd.txt',
                 u'components': components
             }
@@ -290,7 +287,7 @@ class KojiContentGenerator(object):
         try:
             log_path = os.path.join(output_path, "build.log")
             with open(log_path) as build_log:
-                checksum = hashlib.md5(build_log.read()).hexdigest()
+                checksum = hashlib.md5(build_log.read().encode('utf-8')).hexdigest()
             stat = os.stat(log_path)
             ret.append(
                 {
diff --git a/module_build_service/builder/MockModuleBuilder.py b/module_build_service/builder/MockModuleBuilder.py
index 0ce30fa0..0ebb4765 100644
--- a/module_build_service/builder/MockModuleBuilder.py
+++ b/module_build_service/builder/MockModuleBuilder.py
@@ -495,6 +495,9 @@ class MockModuleBuilder(GenericBuilder):
     def list_tasks_for_components(self, component_builds=None, state='active'):
         pass
 
+    def repo_from_tag(cls, config, tag_name, arch):
+        pass
+
 
 class BaseBuilder(object):
     def __init__(self, config, resultsdir):
diff --git a/module_build_service/models.py b/module_build_service/models.py
index 9b459597..42866308 100644
--- a/module_build_service/models.py
+++ b/module_build_service/models.py
@@ -295,13 +295,14 @@ class ModuleBuild(MBSBase):
             mmd_formatted_property = {
                 dep: info['ref'] for dep, info in mbs_xmd[property_name].items()}
             property_json = json.dumps(OrderedDict(sorted(mmd_formatted_property.items())))
-            rv.append(hashlib.sha1(property_json).hexdigest())
+            rv.append(hashlib.sha1(property_json.encode('utf-8')).hexdigest())
         return tuple(rv)
 
     @property
     def context(self):
         if self.build_context and self.runtime_context:
-            combined_hashes = '{0}:{1}'.format(self.build_context, self.runtime_context)
+            combined_hashes = '{0}:{1}'.format(
+                self.build_context, self.runtime_context).encode('utf-8')
             return hashlib.sha1(combined_hashes).hexdigest()[:8]
         else:
             # We can't compute the context because the necessary data isn't there, so return a
diff --git a/module_build_service/scm.py b/module_build_service/scm.py
index 182a4bbb..603f9540 100644
--- a/module_build_service/scm.py
+++ b/module_build_service/scm.py
@@ -110,7 +110,7 @@ class SCM(object):
         found = False
         branches = SCM._run(["git", "branch", "-r", "--contains", self.commit],
                             chdir=self.sourcedir)[1]
-        for branch in branches.split("\n"):
+        for branch in branches.decode('utf-8').split("\n"):
             branch = branch.strip()
             if branch[len("origin/"):] == self.branch:
                 found = True
@@ -203,7 +203,7 @@ class SCM(object):
             # So the dictionary ends up in the format of
             # {"master": "bf028e573e7c18533d89c7873a411de92d4d913e"...}.
             branches = {}
-            for branch_and_ref in output.strip().split("\n"):
+            for branch_and_ref in output.decode('utf-8').strip().split("\n"):
                 # Only look at refs/heads/* and not refs/remotes/origin/*
                 if "refs/heads/" not in branch_and_ref:
                     continue
@@ -253,7 +253,7 @@ class SCM(object):
                     shutil.rmtree(td)
 
             if output:
-                return str(output.strip('\n'))
+                return str(output.decode('utf-8').strip('\n'))
 
             raise UnprocessableEntity(
                 'The full commit hash of "{0}" for "{1}" could not be found'
diff --git a/module_build_service/utils.py b/module_build_service/utils.py
index 7c511164..1a8abfd4 100644
--- a/module_build_service/utils.py
+++ b/module_build_service/utils.py
@@ -33,7 +33,6 @@ import kobo.rpmlib
 import inspect
 import hashlib
 from functools import wraps
-
 import modulemd
 import yaml
 
@@ -68,8 +67,8 @@ def retry(timeout=conf.net_timeout, interval=conf.net_retry_interval, wait_on=Ex
                     log.warn("Exception %r raised from %r.  Retry in %rs" % (
                         e, function, interval))
                     time.sleep(interval)
-                if (time.time() - start) >= timeout:
-                    raise  # This re-raises the last exception.
+                    if (time.time() - start) >= timeout:
+                        raise  # This re-raises the last exception.
         return inner
     return wrapper
 
@@ -675,7 +674,12 @@ def load_local_builds(local_build_nsvs, session=None):
         pass
 
     # Sort with the biggest version first
-    builds.sort(lambda a, b: -cmp(a[2], b[2]))
+    try:
+        # py27
+        builds.sort(lambda a, b: -cmp(a[2], b[2]))
+    except TypeError:
+        # py3
+        builds.sort(key=lambda a: a[2], reverse=True)
 
     for build_id in local_build_nsvs:
         parts = build_id.split(':')
@@ -1470,7 +1474,7 @@ def get_rpm_release(module_build):
     :return: a string of the module's dist tag
     """
     dist_str = '.'.join([module_build.name, module_build.stream, str(module_build.version),
-                         str(module_build.context)])
+                         str(module_build.context)]).encode('utf-8')
     dist_hash = hashlib.sha1(dist_str).hexdigest()[:8]
     return "{prefix}{index}+{dist_hash}".format(
         prefix=conf.default_dist_tag_prefix,
diff --git a/module_build_service/views.py b/module_build_service/views.py
index 52cdc839..45b1050a 100644
--- a/module_build_service/views.py
+++ b/module_build_service/views.py
@@ -30,6 +30,7 @@ import json
 import module_build_service.auth
 from flask import request, jsonify, url_for
 from flask.views import MethodView
+from builtins import str
 
 from module_build_service import app, conf, log, models, db, version
 from module_build_service.utils import (
@@ -329,7 +330,7 @@ class SCMHandler(BaseHandler):
         branch = self.data["branch"]
 
         # python-modulemd expects this to be bytes, not unicode.
-        if isinstance(branch, unicode):
+        if isinstance(branch, str):
             branch = branch.encode('utf-8')
 
         return submit_module_build_from_scm(self.username, url, branch,
diff --git a/tests/test_build/test_build.py b/tests/test_build/test_build.py
index 553567e5..3edcc24d 100644
--- a/tests/test_build/test_build.py
+++ b/tests/test_build/test_build.py
@@ -146,6 +146,9 @@ class FakeModuleBuilder(GenericBuilder):
     def buildroot_add_dependency(self, dependencies):
         pass
 
+    def repo_from_tag(self, config, tag_name, arch):
+        pass
+
     def buildroot_add_artifacts(self, artifacts, install=False):
         if FakeModuleBuilder.on_buildroot_add_artifacts_cb:
             FakeModuleBuilder.on_buildroot_add_artifacts_cb(self, artifacts, install)
@@ -484,17 +487,19 @@ class TestBuild:
     def test_submit_build_with_optional_params(self, mocked_get_user, conf_system, dbg):
         params = {'branch': 'master', 'scmurl': 'git://pkgs.stg.fedoraproject.org/modules/'
                             'testmodule.git?#620ec77321b2ea7b0d67d82992dda3e1d67055b4'}
+        not_existing_param = {"not_existing_param": "foo"}
+        copr_owner_param = {"copr_owner": "foo"}
 
         def submit(data):
             rv = self.client.post('/module-build-service/1/module-builds/', data=json.dumps(data))
             return json.loads(rv.data)
 
-        data = submit(dict(params.items() + {"not_existing_param": "foo"}.items()))
+        data = submit(dict(params, **not_existing_param))
         assert "The request contains unspecified parameters:" in data["message"]
         assert "not_existing_param" in data["message"]
         assert data["status"] == 400
 
-        data = submit(dict(params.items() + {"copr_owner": "foo"}.items()))
+        data = submit(dict(params, **copr_owner_param))
         assert "The request contains parameters specific to Copr builder" in data["message"]
 
     @patch('module_build_service.auth.get_user', return_value=user)
diff --git a/tests/test_builder/test_koji.py b/tests/test_builder/test_koji.py
index c6f72bca..a2cd88c0 100644
--- a/tests/test_builder/test_koji.py
+++ b/tests/test_builder/test_koji.py
@@ -300,6 +300,7 @@ class TestKojiBuilder:
             # getTaskDescendents response
             [[{'1': [], '2': [], '3': [{'weight': 1.0}, {'weight': 1.0}]}]]
         ]
+        session.getAverageBuildDuration.return_value = None
         get_session.return_value = session
 
         weights = KojiModuleBuilder.get_build_weights(["httpd", "apr"])
@@ -320,6 +321,7 @@ class TestKojiBuilder:
             # getTaskDescendents response
             [[{'1': [], '2': [], '3': [{'weight': 1.0}, {'weight': 1.0}]}]]
         ]
+        session.getAverageBuildDuration.return_value = None
         get_session.return_value = session
 
         weights = KojiModuleBuilder.get_build_weights(["httpd", "apr"])
@@ -333,6 +335,7 @@ class TestKojiBuilder:
         session = MagicMock()
         session.getLoggedInUser.return_value = {"id": 123}
         session.multiCall.side_effect = [[[1], [2]], []]
+        session.getAverageBuildDuration.return_value = None
         get_session.return_value = session
 
         weights = KojiModuleBuilder.get_build_weights(["httpd", "apr"])
@@ -349,6 +352,7 @@ class TestKojiBuilder:
         session = MagicMock()
         session.getLoggedInUser.return_value = {"id": 123}
         session.multiCall.side_effect = [[], []]
+        session.getAverageBuildDuration.return_value = None
         get_session.return_value = session
 
         weights = KojiModuleBuilder.get_build_weights(["httpd", "apr"])
@@ -359,5 +363,8 @@ class TestKojiBuilder:
 
     @patch('module_build_service.builder.KojiModuleBuilder.KojiModuleBuilder.get_session')
     def test_get_build_weights_getLoggedInUser_failed(self, get_session):
+        session = MagicMock()
+        session.getAverageBuildDuration.return_value = None
+        get_session.return_value = session
         weights = KojiModuleBuilder.get_build_weights(["httpd", "apr"])
         assert weights == {"httpd": 1.5, "apr": 1.5}
diff --git a/tests/test_logger.py b/tests/test_logger.py
index b7251183..f2452787 100644
--- a/tests/test_logger.py
+++ b/tests/test_logger.py
@@ -36,10 +36,20 @@ class TestLogger:
 
     def setup_method(self, test_method):
         init_data(1)
-        test_id = '.'.join([
-            path.splitext(path.basename(__file__))[0],
-            test_method.im_class.__name__,
-            test_method.im_func.__name__])
+        log.debug(test_method.__module__)
+        try:
+            # py2
+            test_id = '.'.join([
+                path.splitext(path.basename(__file__))[0],
+                test_method.im_class.__name__,
+                test_method.im_func.__name__])
+        except AttributeError:
+            # py3
+            test_id = '.'.join([
+                path.splitext(path.basename(__file__))[0],
+                test_method.__self__.__class__.__name__,
+                test_method.__self__.__class__.__name__])
+
         self.base = tempfile.mkdtemp(prefix='mbs-', suffix='-%s' % test_id)
         self.name_format = "build-{id}.log"
         print("Storing build logs in %r" % self.base)
diff --git a/tests/test_scm.py b/tests/test_scm.py
index 59ac93a5..0b639f3a 100644
--- a/tests/test_scm.py
+++ b/tests/test_scm.py
@@ -140,7 +140,7 @@ class TestSCMModule:
 
     @patch.object(module_build_service.scm.SCM, '_run')
     def test_get_latest_ignore_origin(self, mock_run):
-        output = """\
+        output = b"""\
 58379ef7887cbc91b215bacd32430628c92bc869\tHEAD
 58379ef7887cbc91b215bacd32430628c92bc869\trefs/heads/master
 10a651f39911a07d85fe87fcfe91999545e44ae0\trefs/remotes/origin/master
diff --git a/tests/test_utils/test_utils.py b/tests/test_utils/test_utils.py
index c05cf1c6..627c1192 100644
--- a/tests/test_utils/test_utils.py
+++ b/tests/test_utils/test_utils.py
@@ -559,6 +559,9 @@ class DummyModuleBuilder(GenericBuilder):
     def list_tasks_for_components(self, component_builds=None, state='active'):
         pass
 
+    def repo_from_tag(self, config, tag_name, arch):
+        pass
+
 
 @patch("module_build_service.builder.GenericBuilder.default_buildroot_groups",
        return_value={'build': [], 'srpm-build': []})
diff --git a/tests/test_views/test_views.py b/tests/test_views/test_views.py
index e68d2b62..159a77f2 100644
--- a/tests/test_views/test_views.py
+++ b/tests/test_views/test_views.py
@@ -103,7 +103,7 @@ class FakeSCM(object):
         return self.sourcedir
 
     def get_latest(self, ref='master'):
-        return hashlib.sha1(ref).hexdigest()[:10]
+        return hashlib.sha1(ref.encode('utf-8')).hexdigest()[:10]
 
     def get_module_yaml(self):
         return path.join(self.sourcedir, self.name + ".yaml")
diff --git a/tox.ini b/tox.ini
index 8b153b45..a8d9c8d1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = flake8, py27
+envlist = flake8, py27, py3
 
 [flake8]
 max-line-length = 100