diff --git a/tools/aggregate_entropy_stats.py b/tools/aggregate_entropy_stats.py
index 7cb4d18..0311681 100644
--- a/tools/aggregate_entropy_stats.py
+++ b/tools/aggregate_entropy_stats.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ## Copyright (c) 2017, Alliance for Open Media. All rights reserved
 ##
 ## This source code is subject to the terms of the BSD 2 Clause License and
diff --git a/tools/diff.py b/tools/diff.py
index bac6aab..7bb6b7f 100644
--- a/tools/diff.py
+++ b/tools/diff.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ##
 ## Copyright (c) 2016, Alliance for Open Media. All rights reserved
 ##
diff --git a/tools/gen_constrained_tokenset.py b/tools/gen_constrained_tokenset.py
index 5d12ee1..f5b0816 100755
--- a/tools/gen_constrained_tokenset.py
+++ b/tools/gen_constrained_tokenset.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 ##
 ## Copyright (c) 2016, Alliance for Open Media. All rights reserved
 ##
@@ -108,7 +108,7 @@
   for q in range(1, 256):
     parray = get_quantized_spareto(q / 256., beta, bits, first_token)
     assert parray.sum() == 2**bits
-    print '{', ', '.join('%d' % i for i in parray), '},'
+    print('{', ', '.join('%d' % i for i in parray), '},')
 
 
 if __name__ == '__main__':
diff --git a/tools/intersect-diffs.py b/tools/intersect-diffs.py
index df13c4e..9601836 100755
--- a/tools/intersect-diffs.py
+++ b/tools/intersect-diffs.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ##
 ## Copyright (c) 2016, Alliance for Open Media. All rights reserved
 ##
@@ -71,7 +71,7 @@
                 break
 
     if out_hunks:
-        print FormatDiffHunks(out_hunks)
+        print(FormatDiffHunks(out_hunks))
         sys.exit(1)
 
 if __name__ == "__main__":
diff --git a/tools/lint-hunks.py b/tools/lint-hunks.py
index d02bee1..2267b5e 100755
--- a/tools/lint-hunks.py
+++ b/tools/lint-hunks.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 ##
 ## Copyright (c) 2016, Alliance for Open Media. All rights reserved
 ##
@@ -12,7 +12,7 @@
 """Performs style checking on each diff hunk."""
 import getopt
 import os
-import StringIO
+import io
 import subprocess
 import sys
 
@@ -65,21 +65,21 @@
     try:
         try:
             opts, args = getopt.getopt(argv[1:], SHORT_OPTIONS, LONG_OPTIONS)
-        except getopt.error, msg:
+        except getopt.error as msg:
             raise Usage(msg)
 
         # process options
         for o, _ in opts:
             if o in ("-h", "--help"):
-                print __doc__
+                print(__doc__)
                 sys.exit(0)
 
         if args and len(args) > 1:
-            print __doc__
+            print(__doc__)
             sys.exit(0)
 
         # Find the fully qualified path to the root of the tree
-        tl = Subprocess(TOPLEVEL_CMD, stdout=subprocess.PIPE)
+        tl = Subprocess(TOPLEVEL_CMD, stdout=subprocess.PIPE, text=True)
         tl = tl.communicate()[0].strip()
 
         # See if we're working on the index or not.
@@ -95,9 +95,9 @@
 
         # Get a list of all affected lines
         file_affected_line_map = {}
-        p = Subprocess(diff_cmd, stdout=subprocess.PIPE)
+        p = Subprocess(diff_cmd, stdout=subprocess.PIPE, text=True)
         stdout = p.communicate()[0]
-        for hunk in diff.ParseDiffHunks(StringIO.StringIO(stdout)):
+        for hunk in diff.ParseDiffHunks(io.StringIO(stdout)):
             filename = hunk.right.filename[2:]
             if filename not in file_affected_line_map:
                 file_affected_line_map[filename] = set()
@@ -105,9 +105,11 @@
 
         # Run each affected file through cpplint
         lint_failed = False
-        for filename, affected_lines in file_affected_line_map.iteritems():
+        for filename, affected_lines in file_affected_line_map.items():
             if filename.split(".")[-1] not in ("c", "h", "cc"):
                 continue
+            if filename.startswith("third_party"):
+                continue
 
             if args:
                 # File contents come from git
@@ -129,17 +131,17 @@
                     continue
                 warning_line_num = int(fields[1])
                 if warning_line_num in affected_lines:
-                    print "%s:%d:%s"%(filename, warning_line_num,
-                                      ":".join(fields[2:]))
+                    print("%s:%d:%s"%(filename, warning_line_num,
+                                      ":".join(fields[2:])))
                     lint_failed = True
 
         # Set exit code if any relevant lint errors seen
         if lint_failed:
             return 1
 
-    except Usage, err:
-        print >>sys.stderr, err
-        print >>sys.stderr, "for help use --help"
+    except Usage as err:
+        print(err, file=sys.stderr)
+        print("for help use --help", file=sys.stderr)
         return 2
 
 if __name__ == "__main__":
diff --git a/tools/wrap-commit-msg.py b/tools/wrap-commit-msg.py
index 1c78824..c51ed09 100755
--- a/tools/wrap-commit-msg.py
+++ b/tools/wrap-commit-msg.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ##
 ## Copyright (c) 2016, Alliance for Open Media. All rights reserved
 ##