diff --git a/nilmrun/_version.py b/nilmrun/_version.py
index b3fe6f1..716b34a 100644
--- a/nilmrun/_version.py
+++ b/nilmrun/_version.py
@@ -86,20 +86,20 @@ def run_command(commands, args, cwd=None, verbose=False, hide_stderr=False,
             if e.errno == errno.ENOENT:
                 continue
             if verbose:
-                print("unable to run %s" % dispcmd)
+                print(("unable to run %s" % dispcmd))
                 print(e)
             return None, None
     else:
         if verbose:
-            print("unable to find command, tried %s" % (commands,))
+            print(("unable to find command, tried %s" % (commands,)))
         return None, None
     stdout = p.communicate()[0].strip()
     if sys.version_info[0] >= 3:
         stdout = stdout.decode()
     if p.returncode != 0:
         if verbose:
-            print("unable to run %s (error)" % dispcmd)
-            print("stdout was %s" % stdout)
+            print(("unable to run %s (error)" % dispcmd))
+            print(("stdout was %s" % stdout))
         return None, p.returncode
     return stdout, p.returncode
 
@@ -124,8 +124,8 @@ def versions_from_parentdir(parentdir_prefix, root, verbose):
             root = os.path.dirname(root)  # up a level
 
     if verbose:
-        print("Tried directories %s but none started with prefix %s" %
-              (str(rootdirs), parentdir_prefix))
+        print(("Tried directories %s but none started with prefix %s" %
+              (str(rootdirs), parentdir_prefix)))
     raise NotThisMethod("rootdir doesn't start with parentdir_prefix")
 
 
@@ -192,15 +192,15 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         # "stabilization", as well as "HEAD" and "master".
         tags = set([r for r in refs if re.search(r'\d', r)])
         if verbose:
-            print("discarding '%s', no digits" % ",".join(refs - tags))
+            print(("discarding '%s', no digits" % ",".join(refs - tags)))
     if verbose:
-        print("likely tags: %s" % ",".join(sorted(tags)))
+        print(("likely tags: %s" % ",".join(sorted(tags))))
     for ref in sorted(tags):
         # sorting will prefer e.g. "2.0" over "2.0rc1"
         if ref.startswith(tag_prefix):
             r = ref[len(tag_prefix):]
             if verbose:
-                print("picking %s" % r)
+                print(("picking %s" % r))
             return {"version": r,
                     "full-revisionid": keywords["full"].strip(),
                     "dirty": False, "error": None,
@@ -229,7 +229,7 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
                           hide_stderr=True)
     if rc != 0:
         if verbose:
-            print("Directory %s not under git control" % root)
+            print(("Directory %s not under git control" % root))
         raise NotThisMethod("'git rev-parse --git-dir' returned error")
 
     # if there is a tag matching tag_prefix, this yields TAG-NUM-gHEX[-dirty]
@@ -278,7 +278,7 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
         if not full_tag.startswith(tag_prefix):
             if verbose:
                 fmt = "tag '%s' doesn't start with prefix '%s'"
-                print(fmt % (full_tag, tag_prefix))
+                print((fmt % (full_tag, tag_prefix)))
             pieces["error"] = ("tag '%s' doesn't start with prefix '%s'"
                                % (full_tag, tag_prefix))
             return pieces
diff --git a/nilmrun/processmanager.py b/nilmrun/processmanager.py
index a190658..1caca72 100644
--- a/nilmrun/processmanager.py
+++ b/nilmrun/processmanager.py
@@ -4,7 +4,7 @@ from nilmdb.utils.printf import *
 
 import threading
 import subprocess
-import cStringIO
+import io
 import sys
 import os
 import signal
@@ -23,7 +23,7 @@ class LogReceiver(object):
     and stores them locally."""
     def __init__(self, pipe):
         self.pipe = pipe
-        self.log = cStringIO.StringIO()
+        self.log = io.StringIO()
         self.thread = threading.Thread(target = self.run)
         self.thread.start()
 
@@ -39,7 +39,7 @@ class LogReceiver(object):
         return self.log.getvalue()
 
     def clear(self):
-        self.log = cStringIO.StringIO()
+        self.log = io.StringIO()
 
 class Process(object):
     """Spawn and manage a subprocess, and capture its output."""
@@ -197,7 +197,7 @@ class ProcessManager(object):
 
     def _atexit(self):
         # Kill remaining processes, remove their dirs
-        for pid in self.processes.keys():
+        for pid in list(self.processes.keys()):
             try:
                 self.processes[pid].terminate()
                 del self.processes[pid]
@@ -207,7 +207,7 @@ class ProcessManager(object):
                 pass
 
     def __iter__(self):
-        return iter(self.processes.keys())
+        return iter(list(self.processes.keys()))
 
     def __getitem__(self, key):
         return self.processes[key]
diff --git a/scripts/nilmrun_server.py b/scripts/nilmrun_server.py
index 9946180..b01e175 100755
--- a/scripts/nilmrun_server.py
+++ b/scripts/nilmrun_server.py
@@ -39,20 +39,20 @@ def main():
 
     # Print info
     if not args.quiet:
-        print "NilmRun version: %s" % nilmrun.__version__
-        print ("Note: This server does not do any authentication! " +
-               "Anyone who can connect can run arbitrary commands.")
+        print("NilmRun version: %s" % nilmrun.__version__)
+        print(("Note: This server does not do any authentication! " +
+               "Anyone who can connect can run arbitrary commands."))
         if args.address == '0.0.0.0' or args.address == '::':
             host = socket.getfqdn()
         else:
             host = args.address
-        print "Server URL: http://%s:%d/" % ( host, args.port)
-        print "----"
+        print("Server URL: http://%s:%d/" % ( host, args.port))
+        print("----")
 
     server.start(blocking = True)
 
     if not args.quiet:
-        print "Shutting down"
+        print("Shutting down")
 
 if __name__ == "__main__":
     main()
diff --git a/scripts/run.py b/scripts/run.py
index 8d3c207..55af4f9 100755
--- a/scripts/run.py
+++ b/scripts/run.py
@@ -37,7 +37,7 @@ def main():
 
     # If we're detaching, just print the PID
     if args.detach:
-        print pid
+        print(pid)
         raise SystemExit(0)
 
     # Otherwise, watch the log output, and kill the process when it's done
diff --git a/tests/test_nilmrun.py b/tests/test_nilmrun.py
index 779c1b5..28c5239 100644
--- a/tests/test_nilmrun.py
+++ b/tests/test_nilmrun.py
@@ -15,14 +15,15 @@ import distutils.version
 import os
 import sys
 import threading
-import cStringIO
+import io
 import simplejson as json
 import unittest
 import warnings
 import time
 import re
-import urllib2
-from urllib2 import urlopen, HTTPError
+import urllib.request, urllib.error, urllib.parse
+from urllib.request import urlopen
+from urllib.error import HTTPError
 import requests
 import pprint
 import textwrap
@@ -391,12 +392,12 @@ class TestClient(object):
 
         # Unicode should work
         verify("echo -n hello", "hello")
-        verify(u"echo -n ☠", u"☠")
-        verify("echo -ne \\\\xe2\\\\x98\\\\xa0", u"☠")
+        verify("echo -n ☠", "☠")
+        verify("echo -ne \\\\xe2\\\\x98\\\\xa0", "☠")
 
         # Programs that spit out invalid UTF-8 should get replacement
         # markers
-        verify("echo -ne \\\\xae", u"\ufffd")
+        verify("echo -ne \\\\xae", "\ufffd")
 
     def test_client_11_atexit(self):
         # Leave a directory and running process behind, for the atexit
diff --git a/tests/testutil/helpers.py b/tests/testutil/helpers.py
index b736bd6..90477a3 100644
--- a/tests/testutil/helpers.py
+++ b/tests/testutil/helpers.py
@@ -1,7 +1,7 @@
 # Just some helpers for test functions
 
 def myrepr(x):
-    if isinstance(x, basestring):
+    if isinstance(x, str):
         return '"' + x + '"'
     else:
         return repr(x)
diff --git a/versioneer.py b/versioneer.py
index 64fea1c..d3e699c 100644
--- a/versioneer.py
+++ b/versioneer.py
@@ -276,11 +276,11 @@ https://creativecommons.org/publicdomain/zero/1.0/ .
 
 """
 
-from __future__ import print_function
+
 try:
     import configparser
 except ImportError:
-    import ConfigParser as configparser
+    import configparser as configparser
 import errno
 import json
 import os