diff --git a/test/plugin/test_out_google_cloud.rb b/test/plugin/test_out_google_cloud.rb
index <HASH>..<HASH> 100644
--- a/test/plugin/test_out_google_cloud.rb
+++ b/test/plugin/test_out_google_cloud.rb
@@ -400,6 +400,7 @@ class GoogleCloudOutputTest < Test::Unit::TestCase
   end
 
   def test_one_log_ec2
+    ENV['GOOGLE_APPLICATION_CREDENTIALS'] = 'test/plugin/data/credentials.json'
     setup_ec2_metadata_stubs
     setup_logging_stubs
     d = create_driver(CONFIG_EC2_PROJECT_ID)
Add missing credentials for EC2 logging test.

This test was picking up the credentials from my local filesystem
and succeeding, but failed on travis.  Setting the credentials
explicitly makes it (properly) pass everywhere.