Index: test/runners/firefox_download.js
===================================================================
--- a/test/runners/firefox_download.js
+++ b/test/runners/firefox_download.js
@@ -87,7 +87,7 @@
   // Also uninstaller will need to be run.
   return new Promise((resolve, reject) =>
   {
-    exec([archive, `/extractdir=${browserDir}`].join(" "),
+    exec(`"${archive}" /extractdir=${browserDir}`,
          err =>
          {
            if (err)