diff --git a/src/test/harness/contenttest/contenttest.rs b/src/test/harness/contenttest/contenttest.rs
index 861c758d62b..855f75ebb18 100644
--- a/src/test/harness/contenttest/contenttest.rs
+++ b/src/test/harness/contenttest/contenttest.rs
@@ -85,7 +85,7 @@ fn run_test(file: ~str) {
     let path = os::make_absolute(&Path::new(file));
     // FIXME (#1094): not the right way to transform a path
     let infile = ~"file://" + path.display().to_str();
-    let res = run::process_output("./servo", [infile]);
+    let res = run::process_output("./servo", [~"-z", infile]);
     let out = str::from_utf8(res.output);
     io::print(out);
     let lines: ~[&str] = out.split_iter('\n').collect();