diff --git a/Tests/Functional/xctest_checker/xctest_checker.py b/Tests/Functional/xctest_checker/xctest_checker.py
index 363d3e139..a185cf7fb 100755
--- a/Tests/Functional/xctest_checker/xctest_checker.py
+++ b/Tests/Functional/xctest_checker/xctest_checker.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # xctest_checker.py - Verify XCTest output -*- python -*-
 #
 # This source file is part of the Swift.org open source project
diff --git a/Tests/Functional/xctest_checker/xctest_checker/main.py b/Tests/Functional/xctest_checker/xctest_checker/main.py
index 5177d59b6..5785ead0b 100644
--- a/Tests/Functional/xctest_checker/xctest_checker/main.py
+++ b/Tests/Functional/xctest_checker/xctest_checker/main.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # xctest_checker/main.py - Entry point for xctest_checker -*- python -*-
 #
 # This source file is part of the Swift.org open source project
diff --git a/build_script.py b/build_script.py
index bd90ebf89..92bc9e0d7 100755
--- a/build_script.py
+++ b/build_script.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # build_script.py - Build, install, and test XCTest -*- python -*-
 #
 # This source file is part of the Swift.org open source project