diff --git a/.travis.yml b/.travis.yml
index ffb1bc46f2d960..62557dc8fd37ae 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -39,6 +39,10 @@ matrix:
       compiler:
       script: ci/test-documentation.sh
       after_failure:
+    - env: jobname=LintPython
+      language: python
+      before_install: pip install flake8
+      script: flake8 . --count --select=E9,F63,F72,F82 --show-source --statistics
 
 before_install: ci/install-dependencies.sh
 script: ci/run-build-and-tests.sh
diff --git a/contrib/fast-import/import-zips.py b/contrib/fast-import/import-zips.py
index d12c2962230b80..138194475cbc71 100755
--- a/contrib/fast-import/import-zips.py
+++ b/contrib/fast-import/import-zips.py
@@ -8,6 +8,7 @@
 ##  python import-zips.py *.zip
 ##  git log --stat import-zips
 
+from __future__ import print_function
 from os import popen, path
 from sys import argv, exit, hexversion, stderr
 from time import mktime
@@ -19,7 +20,7 @@
     exit(1)
 
 if len(argv) < 2:
-    print 'usage:', argv[0], '<zipfile>...'
+    print('usage:', argv[0], '<zipfile>...')
     exit(1)
 
 branch_ref = 'refs/heads/import-zips'
diff --git a/contrib/hg-to-git/hg-to-git.py b/contrib/hg-to-git/hg-to-git.py
index de3f81667ed972..1d5e5156a4f1f3 100755
--- a/contrib/hg-to-git/hg-to-git.py
+++ b/contrib/hg-to-git/hg-to-git.py
@@ -18,6 +18,7 @@
     along with this program; if not, see <http://www.gnu.org/licenses/>.
 """
 
+from __future__ import print_function
 import os, os.path, sys
 import tempfile, pickle, getopt
 import re
@@ -42,7 +43,7 @@
 
 def usage():
 
-        print """\
+        print("""\
 %s: [OPTIONS] <hgprj>
 
 options:
@@ -54,7 +55,7 @@ def usage():
 
 required:
     hgprj:  name of the HG project to import (directory)
-""" % sys.argv[0]
+""" % sys.argv[0])
 
 #------------------------------------------------------------------------------
 
@@ -104,22 +105,22 @@ def getgitenv(user, date):
 if state:
     if os.path.exists(state):
         if verbose:
-            print 'State does exist, reading'
+            print('State does exist, reading')
         f = open(state, 'r')
         hgvers = pickle.load(f)
     else:
-        print 'State does not exist, first run'
+        print('State does not exist, first run')
 
 sock = os.popen('hg tip --template "{rev}"')
 tip = sock.read()
 if sock.close():
     sys.exit(1)
 if verbose:
-    print 'tip is', tip
+    print('tip is', tip)
 
 # Calculate the branches
 if verbose:
-    print 'analysing the branches...'
+    print('analysing the branches...')
 hgchildren["0"] = ()
 hgparents["0"] = (None, None)
 hgbranch["0"] = "master"
@@ -155,7 +156,7 @@ def getgitenv(user, date):
             hgbranch[str(cset)] = "branch-" + str(cset)
 
 if not hgvers.has_key("0"):
-    print 'creating repository'
+    print('creating repository')
     os.system('git init')
 
 # loop through every hg changeset
@@ -180,27 +181,27 @@ def getgitenv(user, date):
     os.write(fdcomment, csetcomment)
     os.close(fdcomment)
 
-    print '-----------------------------------------'
-    print 'cset:', cset
-    print 'branch:', hgbranch[str(cset)]
-    print 'user:', user
-    print 'date:', date
-    print 'comment:', csetcomment
+    print('-----------------------------------------')
+    print('cset:', cset)
+    print('branch:', hgbranch[str(cset)])
+    print('user:', user)
+    print('date:', date)
+    print('comment:', csetcomment)
     if parent:
-	print 'parent:', parent
+	    print('parent:', parent)
     if mparent:
-        print 'mparent:', mparent
+        print('mparent:', mparent)
     if tag:
-        print 'tag:', tag
-    print '-----------------------------------------'
+        print('tag:', tag)
+    print('-----------------------------------------')
 
     # checkout the parent if necessary
     if cset != 0:
         if hgbranch[str(cset)] == "branch-" + str(cset):
-            print 'creating new branch', hgbranch[str(cset)]
+            print('creating new branch', hgbranch[str(cset)])
             os.system('git checkout -b %s %s' % (hgbranch[str(cset)], hgvers[parent]))
         else:
-            print 'checking out branch', hgbranch[str(cset)]
+            print('checking out branch', hgbranch[str(cset)])
             os.system('git checkout %s' % hgbranch[str(cset)])
 
     # merge
@@ -209,7 +210,7 @@ def getgitenv(user, date):
             otherbranch = hgbranch[mparent]
         else:
             otherbranch = hgbranch[parent]
-        print 'merging', otherbranch, 'into', hgbranch[str(cset)]
+        print('merging', otherbranch, 'into', hgbranch[str(cset)])
         os.system(getgitenv(user, date) + 'git merge --no-commit -s ours "" %s %s' % (hgbranch[str(cset)], otherbranch))
 
     # remove everything except .git and .hg directories
@@ -233,12 +234,12 @@ def getgitenv(user, date):
 
     # delete branch if not used anymore...
     if mparent and len(hgchildren[str(cset)]):
-        print "Deleting unused branch:", otherbranch
+        print("Deleting unused branch:", otherbranch)
         os.system('git branch -d %s' % otherbranch)
 
     # retrieve and record the version
     vvv = os.popen('git show --quiet --pretty=format:%H').read()
-    print 'record', cset, '->', vvv
+    print('record', cset, '->', vvv)
     hgvers[str(cset)] = vvv
 
 if hgnewcsets >= opt_nrepack and opt_nrepack != -1:
@@ -247,7 +248,7 @@ def getgitenv(user, date):
 # write the state for incrementals
 if state:
     if verbose:
-        print 'Writing state'
+        print('Writing state')
     f = open(state, 'w')
     pickle.dump(hgvers, f)
 
diff --git a/git-p4.py b/git-p4.py
index 3991e7d1a7fc4d..9faee25db26da3 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -36,6 +36,8 @@
     unicode = str
     bytes = bytes
     basestring = (str,bytes)
+    raw_input = input
+    from functools import reduce
 else:
     # 'unicode' exists, must be Python 2
     str = str
@@ -3968,6 +3970,7 @@ def renameBranch(self, branch_name):
                 break
 
         if not found:
+            sync = P4Sync()
             sys.exit("gave up trying to rename existing branch {0}".format(sync.branch))
 
     def findLastP4Revision(self, starting_point):