diff --git a/tools/run_tests/artifact_targets.py b/tools/run_tests/artifact_targets.py
index 32a98c90b8aad060aff6481de5a5614e24295818..573825699f3a8ce03ccd1e66321282b164e7bc70 100644
--- a/tools/run_tests/artifact_targets.py
+++ b/tools/run_tests/artifact_targets.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2.7
 # Copyright 2016, Google Inc.
 # All rights reserved.
 #
diff --git a/tools/run_tests/distribtest_targets.py b/tools/run_tests/distribtest_targets.py
index 069f2f16cbff884273ca28843ca6e7fec3a0617b..55fee564152ef82393c34bf127f50ee83c42df21 100644
--- a/tools/run_tests/distribtest_targets.py
+++ b/tools/run_tests/distribtest_targets.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2.7
 # Copyright 2016, Google Inc.
 # All rights reserved.
 #
diff --git a/tools/run_tests/package_targets.py b/tools/run_tests/package_targets.py
index 839991e270ea6b8956f5402c1a5c2baae00c1f5d..5bc4b1c9c48ad02e4b187afb5581441fb75c7c15 100644
--- a/tools/run_tests/package_targets.py
+++ b/tools/run_tests/package_targets.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2.7
 # Copyright 2016, Google Inc.
 # All rights reserved.
 #
diff --git a/tools/run_tests/run_interop_tests.py b/tools/run_tests/run_interop_tests.py
index 6ce618eb77907b9727bae27e9b6d3c57ded78b7f..fbc3b3cdf6fadbc13e798b27ffbe85930019d55e 100755
--- a/tools/run_tests/run_interop_tests.py
+++ b/tools/run_tests/run_interop_tests.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2.7
 # Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
diff --git a/tools/run_tests/run_stress_tests.py b/tools/run_tests/run_stress_tests.py
index 193ff2e53a3243c6825bf0dafce0c6cc446caf92..d1faf7d9641c012fda9e3b16488eba931977783e 100755
--- a/tools/run_tests/run_stress_tests.py
+++ b/tools/run_tests/run_stress_tests.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2.7
 # Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
diff --git a/tools/run_tests/task_runner.py b/tools/run_tests/task_runner.py
index e5ecc4867b553d1a5e81e9f6844f1282638e2abb..b42aa17cbbe890d6d1bf59b703e1c8a300b7d490 100755
--- a/tools/run_tests/task_runner.py
+++ b/tools/run_tests/task_runner.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2.7
 # Copyright 2016, Google Inc.
 # All rights reserved.
 #