diff --git a/testing/web-platform/tests/tools/ci/run_tc.py b/testing/web-platform/tests/tools/ci/run_tc.py
index 1cfb41fcaaba5..240517a1ff68b 100755
--- a/testing/web-platform/tests/tools/ci/run_tc.py
+++ b/testing/web-platform/tests/tools/ci/run_tc.py
@@ -109,7 +109,7 @@ def get_parser():
 def start_userspace_oom_killer():
     # Start userspace OOM killer: https://github.com/rfjakob/earlyoom
     # It will report memory usage every minute and prefer to kill browsers.
-    start(["sudo", "earlyoom", "-p", "-r", "60" "--prefer=(chrome|firefox)", "--avoid=python"])
+    start(["sudo", "earlyoom", "-p", "-r", "60", "--prefer=(chrome|firefox)", "--avoid=python"])
 
 
 def make_hosts_file():