diff --git a/appengine/add_timestamps.py b/appengine/add_timestamps.py
index 8cf90b522..af877f3d6 100644
--- a/appengine/add_timestamps.py
+++ b/appengine/add_timestamps.py
@@ -33,7 +33,7 @@ See the current project: `gcloud config get-value project`
 
 Start a venv: `python3 -m venv venv && source venv/bin/activate`
 Inside your vm run `pip install google-cloud-ndb`
-Run the script: `python add_timestamps.py`
+Run the script: `python3 add_timestamps.py`
 """
 
 __author__ = "fenichel@google.com (Rachel Fenichel)"
diff --git a/scripts/gulpfiles/build_tasks.js b/scripts/gulpfiles/build_tasks.js
index 6dc7b86e8..1c90a6cb0 100644
--- a/scripts/gulpfiles/build_tasks.js
+++ b/scripts/gulpfiles/build_tasks.js
@@ -416,7 +416,7 @@ goog.require('Blockly.requires');
  */
 function generateLangfiles(done) {
   // Run js_to_json.py
-  const jsToJsonCmd = `python scripts/i18n/js_to_json.py \
+  const jsToJsonCmd = `python3 scripts/i18n/js_to_json.py \
       --input_file ${path.join('msg', 'messages.js')} \
       --output_dir ${path.join('msg', 'json')} \
       --quiet`;
@@ -454,7 +454,7 @@ function buildLangfiles(done) {
   json_files = json_files.filter(file => file.endsWith('json') &&
       !(new RegExp(/(keys|synonyms|qqq|constants)\.json$/).test(file)));
   json_files = json_files.map(file => path.join('msg', 'json', file));
-  const createMessagesCmd = `python ./scripts/i18n/create_messages.py \
+  const createMessagesCmd = `python3 ./scripts/i18n/create_messages.py \
   --source_lang_file ${path.join('msg', 'json', 'en.json')} \
   --source_synonym_file ${path.join('msg', 'json', 'synonyms.json')} \
   --source_constants_file ${path.join('msg', 'json', 'constants.json')} \
diff --git a/scripts/i18n/common.py b/scripts/i18n/common.py
index 7e568a5f6..0ac733dca 100644
--- a/scripts/i18n/common.py
+++ b/scripts/i18n/common.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 # Code shared by translation conversion scripts.
 #
diff --git a/scripts/i18n/create_messages.py b/scripts/i18n/create_messages.py
index ef489aaf3..70ce61de3 100755
--- a/scripts/i18n/create_messages.py
+++ b/scripts/i18n/create_messages.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 # Generate .js files defining Blockly core and language messages.
 #
diff --git a/scripts/i18n/dedup_json.py b/scripts/i18n/dedup_json.py
index 1329e4758..ccdddf54a 100755
--- a/scripts/i18n/dedup_json.py
+++ b/scripts/i18n/dedup_json.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 # Consolidates duplicate key-value pairs in a JSON file.
 # If the same key is used with different values, no warning is given,
diff --git a/scripts/i18n/js_to_json.py b/scripts/i18n/js_to_json.py
index cd3d4dc2b..8c3a01e11 100755
--- a/scripts/i18n/js_to_json.py
+++ b/scripts/i18n/js_to_json.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 # Gives the translation status of the specified apps and languages.
 #
diff --git a/scripts/i18n/tests.py b/scripts/i18n/tests.py
index 2fd3bc76a..684d73105 100644
--- a/scripts/i18n/tests.py
+++ b/scripts/i18n/tests.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # -*- coding: utf-8 -*-
 
 # Tests of i18n scripts.