--- a/python/mozboot/mozboot/android.py
+++ b/python/mozboot/mozboot/android.py
@@ -130,17 +130,17 @@ def install_mobile_android_sdk_or_ndk(ur
     finally:
         os.chdir(old_path)
 
 
 def get_paths(os_name):
     mozbuild_path = os.environ.get('MOZBUILD_STATE_PATH',
                                    os.path.expanduser(os.path.join('~', '.mozbuild')))
     sdk_path = os.environ.get('ANDROID_SDK_HOME',
-                              os.path.join(mozbuild_path, 'android-sdk-{}'.format(os_name)))
+                              os.path.join(mozbuild_path, 'android-sdk-{0}'.format(os_name)))
     ndk_path = os.environ.get('ANDROID_NDK_HOME',
                               os.path.join(mozbuild_path, 'android-ndk-r11c'))
     return (mozbuild_path, sdk_path, ndk_path)
 
 
 def ensure_dir(dir):
     '''Ensures the given directory exists'''
     if dir and not os.path.exists(dir):
@@ -161,37 +161,37 @@ def ensure_android(os_name, artifact_mod
     `os_name` can be 'linux' or 'macosx'.
     '''
     # The user may have an external Android SDK (in which case we
     # save them a lengthy download), or they may have already
     # completed the download. We unpack to
     # ~/.mozbuild/{android-sdk-$OS_NAME, android-ndk-$VER}.
     mozbuild_path, sdk_path, ndk_path = get_paths(os_name)
     os_tag = 'darwin' if os_name == 'macosx' else os_name
-    sdk_url = 'https://dl.google.com/android/repository/sdk-tools-{}-3859397.zip'.format(os_tag)
+    sdk_url = 'https://dl.google.com/android/repository/sdk-tools-{0}-3859397.zip'.format(os_tag)
     ndk_url = android_ndk_url(os_name)
 
     ensure_android_sdk_and_ndk(mozbuild_path, os_name,
                                sdk_path=sdk_path, sdk_url=sdk_url,
                                ndk_path=ndk_path, ndk_url=ndk_url,
                                artifact_mode=artifact_mode)
 
     if no_interactive:
         # Cribbed from observation and https://stackoverflow.com/a/38381577.
-        path = os.path.join(mozbuild_path, 'android-sdk-{}'.format(os_name), 'licenses')
+        path = os.path.join(mozbuild_path, 'android-sdk-{0}'.format(os_name), 'licenses')
         ensure_dir(path)
 
         licenses = {
             'android-sdk-license': '8933bad161af4178b1185d1a37fbf41ea5269c55',
             'android-sdk-preview-license': '84831b9409646a918e30573bab4c9c91346d8abd',
         }
         for license, tag in licenses.items():
             lname = os.path.join(path, license)
             if not os.path.isfile(lname):
-                open(lname, 'w').write('\n{}\n'.format(tag))
+                open(lname, 'w').write('\n{0}\n'.format(tag))
 
 
     # We expect the |sdkmanager| tool to be at
     # ~/.mozbuild/android-sdk-$OS_NAME/tools/bin/sdkmanager.
     sdkmanager_tool = os.path.join(sdk_path, 'tools', 'bin', 'sdkmanager')
     ensure_android_packages(sdkmanager_tool=sdkmanager_tool)
 
 
@@ -220,31 +220,31 @@ def ensure_android_sdk_and_ndk(mozbuild_
         print(ANDROID_SDK_EXISTS % sdk_path)
     elif os.path.isdir(sdk_path):
         raise NotImplementedError(ANDROID_SDK_TOO_OLD % sdk_path)
     else:
         # The SDK archive used to include a top-level
         # android-sdk-$OS_NAME directory; it no longer does so.  We
         # preserve the old convention to smooth detecting existing SDK
         # installations.
-        install_mobile_android_sdk_or_ndk(sdk_url, os.path.join(mozbuild_path, 'android-sdk-{}'.format(os_name)))
+        install_mobile_android_sdk_or_ndk(sdk_url, os.path.join(mozbuild_path, 'android-sdk-{0}'.format(os_name)))
 
 
 def ensure_android_packages(sdkmanager_tool, packages=None):
     '''
     Use the given sdkmanager tool (like 'sdkmanager') to install required
     Android packages.
     '''
 
     # This tries to install all the required Android packages.  The user
     # may be prompted to agree to the Android license.
     package_file_name = os.path.abspath(os.path.join(os.path.dirname(__file__), 'android-packages.txt'))
     print(INSTALLING_ANDROID_PACKAGES % open(package_file_name, 'rt').read())
     subprocess.check_call([sdkmanager_tool,
-                           '--package_file={}'.format(package_file_name)])
+                           '--package_file={0}'.format(package_file_name)])
 
 
 def suggest_mozconfig(os_name, artifact_mode=False):
     _mozbuild_path, sdk_path, ndk_path = get_paths(os_name)
     if artifact_mode:
         print(MOBILE_ANDROID_ARTIFACT_MODE_MOZCONFIG_TEMPLATE % (sdk_path))
     else:
         print(MOBILE_ANDROID_MOZCONFIG_TEMPLATE % (sdk_path, ndk_path))
@@ -283,17 +283,17 @@ def main(argv):
     if platform.system() == 'Darwin':
         os_name = 'macosx'
     elif platform.system() == 'Linux':
         os_name = 'linux'
     elif platform.system() == 'Windows':
         os_name = 'windows'
     else:
         raise NotImplementedError("We don't support bootstrapping the Android SDK (or Android NDK) "
-                                  "on {} yet!".format(platform.system()))
+                                  "on {0} yet!".format(platform.system()))
 
     ensure_android(os_name, artifact_mode=options.artifact_mode, no_interactive=options.no_interactive)
     suggest_mozconfig(os_name, options.artifact_mode)
 
     return 0
 
 
 if __name__ == '__main__':