diff --git a/support/travis-build.py b/support/travis-build.py
index 3ef09fa4..baefc1d4 100755
--- a/support/travis-build.py
+++ b/support/travis-build.py
@@ -2,7 +2,7 @@
 # Build the project on Travis CI.
 
 from __future__ import print_function
-import errno, os, re, shutil, sys, tempfile, urllib
+import errno, os, re, shutil, subprocess, sys, tempfile, urllib
 from subprocess import call, check_call, check_output, Popen, PIPE, STDOUT
 
 def rmtree_if_exists(dir):