diff --git a/tools/releasetools/check_target_files_signatures.py b/tools/releasetools/check_target_files_signatures.py
index 4b0d4c7..60200a3 100755
--- a/tools/releasetools/check_target_files_signatures.py
+++ b/tools/releasetools/check_target_files_signatures.py
@@ -39,8 +39,11 @@
 
 """
 
+from __future__ import print_function
+
 import logging
 import os
+import os.path
 import re
 import subprocess
 import sys
@@ -49,7 +52,7 @@
 import common
 
 if sys.hexversion < 0x02070000:
-  print >> sys.stderr, "Python 2.7 or newer is required."
+  print("Python 2.7 or newer is required.", file=sys.stderr)
   sys.exit(1)
 
 
@@ -65,8 +68,10 @@
 class MyZipInfo(zipfile.ZipInfo):
   def _decodeExtra(self):
     pass
+
 zipfile.ZipInfo = MyZipInfo
 
+
 OPTIONS = common.OPTIONS
 
 OPTIONS.text = False
@@ -76,28 +81,34 @@
 PROBLEMS = []
 PROBLEM_PREFIX = []
 
+
 def AddProblem(msg):
   PROBLEMS.append(" ".join(PROBLEM_PREFIX) + " " + msg)
+
+
 def Push(msg):
   PROBLEM_PREFIX.append(msg)
+
+
 def Pop():
   PROBLEM_PREFIX.pop()
 
 
 def Banner(msg):
-  print "-" * 70
-  print "  ", msg
-  print "-" * 70
+  print("-" * 70)
+  print("  ", msg)
+  print("-" * 70)
 
 
 def GetCertSubject(cert):
   p = common.Run(["openssl", "x509", "-inform", "DER", "-text"],
                  stdin=subprocess.PIPE,
-                 stdout=subprocess.PIPE)
+                 stdout=subprocess.PIPE,
+                 universal_newlines=False)
   out, err = p.communicate(cert)
   if err and not err.strip():
     return "(error reading cert subject)"
-  for line in out.split("\n"):
+  for line in out.decode().split("\n"):
     line = line.strip()
     if line.startswith("Subject:"):
       return line[8:].strip()
@@ -105,6 +116,7 @@
 
 
 class CertDB(object):
+
   def __init__(self):
     self.certs = {}
 
@@ -132,13 +144,13 @@
           to_load.extend(certs)
 
     for i in to_load:
-      f = open(i)
-      cert = common.ParseCertificate(f.read())
-      f.close()
+      with open(i) as f:
+        cert = common.ParseCertificate(f.read())
       name, _ = os.path.splitext(i)
       name, _ = os.path.splitext(name)
       self.Add(cert, name)
 
+
 ALL_CERTS = CertDB()
 
 
@@ -152,13 +164,14 @@
                     "-outform", "PEM",
                     "-print_certs"],
                    stdin=subprocess.PIPE,
-                   stdout=subprocess.PIPE)
+                   stdout=subprocess.PIPE,
+                   universal_newlines=False)
     out, err = p.communicate(data)
     if err and not err.strip():
-      AddProblem("error reading cert:\n" + err)
+      AddProblem("error reading cert:\n" + err.decode())
       return None
 
-    cert = common.ParseCertificate(out)
+    cert = common.ParseCertificate(out.decode())
     if not cert:
       AddProblem("error parsing cert output")
       return None
@@ -184,22 +197,20 @@
 
   def RecordCerts(self, full_filename):
     out = set()
-    try:
-      f = open(full_filename)
-      apk = zipfile.ZipFile(f, "r")
+    with zipfile.ZipFile(full_filename) as apk:
       pkcs7 = None
       for info in apk.infolist():
-        if info.filename.startswith("META-INF/") and \
-           (info.filename.endswith(".DSA") or info.filename.endswith(".RSA")):
-          pkcs7 = apk.read(info.filename)
-          cert = CertFromPKCS7(pkcs7, info.filename)
+        filename = info.filename
+        if (filename.startswith("META-INF/") and
+            info.filename.endswith((".DSA", ".RSA"))):
+          pkcs7 = apk.read(filename)
+          cert = CertFromPKCS7(pkcs7, filename)
           out.add(cert)
           ALL_CERTS.Add(cert)
       if not pkcs7:
         AddProblem("no signature")
-    finally:
-      f.close()
-      self.certs = frozenset(out)
+
+    self.certs = frozenset(out)
 
   def ReadManifest(self, full_filename):
     p = common.Run(["aapt", "dump", "xmltree", full_filename,
@@ -247,8 +258,8 @@
     # This is the list of wildcards of files we extract from |filename|.
     apk_extensions = ['*.apk', '*.apex']
 
-    self.certmap, compressed_extension = common.ReadApkCerts(
-        zipfile.ZipFile(filename))
+    with zipfile.ZipFile(filename) as input_zip:
+      self.certmap, compressed_extension = common.ReadApkCerts(input_zip)
     if compressed_extension:
       apk_extensions.append('*.apk' + compressed_extension)
 
@@ -287,7 +298,7 @@
     """Look for any instances where packages signed with different
     certs request the same sharedUserId."""
     apks_by_uid = {}
-    for apk in self.apks.itervalues():
+    for apk in self.apks.values():
       if apk.shared_uid:
         apks_by_uid.setdefault(apk.shared_uid, []).append(apk)
 
@@ -302,15 +313,15 @@
 
       AddProblem("different cert sets for packages with uid %s" % (uid,))
 
-      print "uid %s is shared by packages with different cert sets:" % (uid,)
+      print("uid %s is shared by packages with different cert sets:" % (uid,))
       for apk in apks:
-        print "%-*s  [%s]" % (self.max_pkg_len, apk.package, apk.filename)
+        print("%-*s  [%s]" % (self.max_pkg_len, apk.package, apk.filename))
         for cert in apk.certs:
-          print "   ", ALL_CERTS.Get(cert)
-      print
+          print("   ", ALL_CERTS.Get(cert))
+      print()
 
   def CheckExternalSignatures(self):
-    for apk_filename, certname in self.certmap.iteritems():
+    for apk_filename, certname in self.certmap.items():
       if certname == "EXTERNAL":
         # Apps marked EXTERNAL should be signed with the test key
         # during development, then manually re-signed after
@@ -326,25 +337,25 @@
   def PrintCerts(self):
     """Display a table of packages grouped by cert."""
     by_cert = {}
-    for apk in self.apks.itervalues():
+    for apk in self.apks.values():
       for cert in apk.certs:
         by_cert.setdefault(cert, []).append((apk.package, apk))
 
-    order = [(-len(v), k) for (k, v) in by_cert.iteritems()]
+    order = [(-len(v), k) for (k, v) in by_cert.items()]
     order.sort()
 
     for _, cert in order:
-      print "%s:" % (ALL_CERTS.Get(cert),)
+      print("%s:" % (ALL_CERTS.Get(cert),))
       apks = by_cert[cert]
       apks.sort()
       for _, apk in apks:
         if apk.shared_uid:
-          print "  %-*s  %-*s  [%s]" % (self.max_fn_len, apk.filename,
+          print("  %-*s  %-*s  [%s]" % (self.max_fn_len, apk.filename,
                                         self.max_pkg_len, apk.package,
-                                        apk.shared_uid)
+                                        apk.shared_uid))
         else:
-          print "  %-*s  %s" % (self.max_fn_len, apk.filename, apk.package)
-      print
+          print("  %-*s  %s" % (self.max_fn_len, apk.filename, apk.package))
+      print()
 
   def CompareWith(self, other):
     """Look for instances where a given package that exists in both
@@ -365,12 +376,12 @@
             by_certpair.setdefault((other.apks[i].certs,
                                     self.apks[i].certs), []).append(i)
         else:
-          print "%s [%s]: new APK (not in comparison target_files)" % (
-              i, self.apks[i].filename)
+          print("%s [%s]: new APK (not in comparison target_files)" % (
+              i, self.apks[i].filename))
       else:
         if i in other.apks:
-          print "%s [%s]: removed APK (only in comparison target_files)" % (
-              i, other.apks[i].filename)
+          print("%s [%s]: removed APK (only in comparison target_files)" % (
+              i, other.apks[i].filename))
 
     if by_certpair:
       AddProblem("some APKs changed certs")
@@ -378,23 +389,23 @@
       for (old, new), packages in sorted(by_certpair.items()):
         for i, o in enumerate(old):
           if i == 0:
-            print "was", ALL_CERTS.Get(o)
+            print("was", ALL_CERTS.Get(o))
           else:
-            print "   ", ALL_CERTS.Get(o)
+            print("   ", ALL_CERTS.Get(o))
         for i, n in enumerate(new):
           if i == 0:
-            print "now", ALL_CERTS.Get(n)
+            print("now", ALL_CERTS.Get(n))
           else:
-            print "   ", ALL_CERTS.Get(n)
+            print("   ", ALL_CERTS.Get(n))
         for i in sorted(packages):
           old_fn = other.apks[i].filename
           new_fn = self.apks[i].filename
           if old_fn == new_fn:
-            print "  %-*s  [%s]" % (max_pkg_len, i, old_fn)
+            print("  %-*s  [%s]" % (max_pkg_len, i, old_fn))
           else:
-            print "  %-*s  [was: %s; now: %s]" % (max_pkg_len, i,
-                                                  old_fn, new_fn)
-        print
+            print("  %-*s  [was: %s; now: %s]" % (max_pkg_len, i,
+                                                  old_fn, new_fn))
+        print()
 
 
 def main(argv):
@@ -451,9 +462,9 @@
     target_files.CompareWith(compare_files)
 
   if PROBLEMS:
-    print "%d problem(s) found:\n" % (len(PROBLEMS),)
+    print("%d problem(s) found:\n" % (len(PROBLEMS),))
     for p in PROBLEMS:
-      print p
+      print(p)
     return 1
 
   return 0
@@ -464,9 +475,7 @@
     r = main(sys.argv[1:])
     sys.exit(r)
   except common.ExternalError as e:
-    print
-    print "   ERROR: %s" % (e,)
-    print
+    print("\n   ERROR: %s\n" % (e,))
     sys.exit(1)
   finally:
     common.Cleanup()