diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index 38c06764b9b5c81155754ec8ba7cb93bfdbebb73..51008538f274025ff97535cb952dbc39949cc903 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -728,7 +728,7 @@ def _start_port_server(port_server_port):
   if not running:
     port_log = open('portlog.txt', 'w')
     port_server = subprocess.Popen(
-        ['python', 'tools/run_tests/port_server.py', '-p', '%d' % port_server_port],
+        ['python2.7', 'tools/run_tests/port_server.py', '-p', '%d' % port_server_port],
         stderr=subprocess.STDOUT,
         stdout=port_log)
     # ensure port server is up