diff --git a/DEPS b/DEPS
index e08dbd4c..3fcd524d 100644
--- a/DEPS
+++ b/DEPS
@@ -52,7 +52,7 @@ deps = {
 hooks = [
   {
     # Keep the manifest up to date.
-    "action": ["python", "src/src/tools/python/deps-to-manifest.py",
+    "action": ["src/src/tools/python/deps-to-manifest.py",
                "src/DEPS", "src/default.xml"],
   },
 ]
diff --git a/src/tools/python/deps-to-manifest.py b/src/tools/python/deps-to-manifest.py
index 2fcaf771..b614f94f 100755
--- a/src/tools/python/deps-to-manifest.py
+++ b/src/tools/python/deps-to-manifest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 # Copyright 2016 Google LLC
 #
 # Redistribution and use in source and binary forms, with or without
@@ -29,8 +29,6 @@
 
 """Convert gclient's DEPS file to repo's manifest xml file."""
 
-from __future__ import print_function
-
 import argparse
 import os
 import sys
@@ -76,7 +74,8 @@ def ConvertDepsToManifest(deps, manifest):
   """Convert the |deps| file to the |manifest|."""
   # Load the DEPS file data.
   ctx = {}
-  execfile(deps, ctx)
+  with open(deps, 'rb') as file:
+    exec(compile(file.read(), deps, 'exec'), ctx)
 
   new_contents = ''
 
diff --git a/src/tools/python/filter_syms.py b/src/tools/python/filter_syms.py
index caf3693a..8537769e 100644
--- a/src/tools/python/filter_syms.py
+++ b/src/tools/python/filter_syms.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright 2012 Google LLC
 #
 # Redistribution and use in source and binary forms, with or without
@@ -38,7 +38,6 @@ DWARF files and normalize and de-duplicate the FILE records found within,
 updating any references to the FILE records in the other record types.
 """
 
-import macpath
 import ntpath
 import optparse
 import os
@@ -132,8 +131,8 @@ class SymbolFileParser(object):
     Returns:
         The actual path to use when writing the FILE record.
     """
-    return path[len(filter(path.startswith,
-                           self.ignored_prefixes + [''])[0]):]
+    return path[len(next(filter(path.startswith,
+                                self.ignored_prefixes + ['']))):]
 
   def _ParseFileRecord(self, file_record):
     """Parses and corrects a FILE record."""
@@ -193,7 +192,7 @@ def main():
     symbol_parser = SymbolFileParser(sys.stdin, sys.stdout, options.prefixes,
                                      path_handler)
     symbol_parser.Process()
-  except BreakpadParseError, e:
+  except BreakpadParseError as e:
     print >> sys.stderr, 'Got an error while processing symbol file'
     print >> sys.stderr, str(e)
     return 1
diff --git a/src/tools/python/tests/filter_syms_unittest.py b/src/tools/python/tests/filter_syms_unittest.py
index 1081fc73..f6364b8b 100644
--- a/src/tools/python/tests/filter_syms_unittest.py
+++ b/src/tools/python/tests/filter_syms_unittest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright 2012 Google LLC
 #
 # Redistribution and use in source and binary forms, with or without
@@ -29,10 +29,9 @@
 
 """Unit tests for filter_syms.py"""
 
-import cStringIO
+import io
 import ntpath
 import os
-import StringIO
 import sys
 import unittest
 
@@ -44,8 +43,8 @@ import filter_syms
 
 class FilterSysmsTest(unittest.TestCase):
   def assertParsed(self, input_data, ignored_prefixes, expected):
-    input_io = cStringIO.StringIO(input_data)
-    output_io = cStringIO.StringIO()
+    input_io = io.StringIO(input_data)
+    output_io = io.StringIO()
     parser = filter_syms.SymbolFileParser(input_io, output_io,
                                           ignored_prefixes, ntpath)
     parser.Process()
@@ -134,4 +133,4 @@ FUNC 1000 c 0 Function1_1
     self.assertParsed(INPUT, IGNORED_PREFIXES, EXPECTED_OUTPUT)
 
 if __name__ == '__main__':
-  unittest.main()
\ No newline at end of file
+  unittest.main()