diff --git a/test/firefox.sh b/test/firefox.sh
index 6cc7219d4bc9..674981c02d80 100755
--- a/test/firefox.sh
+++ b/test/firefox.sh
@@ -61,7 +61,11 @@ pushd $TEST_ADDON_PATH
 if [ "$1" == "--justrun" ]; then
   echo "running firefox"
   shift
-  firefox -no-remote -profile "$PROFILE_DIRECTORY" "$@"
+  if [ $(uname) == Darwin ]; then
+    open /Applications/Firefox.app --wait-apps --new --args -no-remote -profile "$PROFILE_DIRECTORY" "$@"
+  else
+    firefox -no-remote -profile "$PROFILE_DIRECTORY" "$@"
+  fi
 else
   echo "running tests"
   cfx test --profiledir="$PROFILE_DIRECTORY" --verbose