diff --git a/js/src/tests/jstests.py b/js/src/tests/jstests.py
index 307462f02049..63eff5ca9a56 100755
--- a/js/src/tests/jstests.py
+++ b/js/src/tests/jstests.py
@@ -295,7 +295,7 @@ def parse_args():
     return (options, prefix, requested_paths, excluded_paths)
 
 
-def load_wpt_tests(requested_paths, excluded_paths, debug):
+def load_wpt_tests(requested_paths, excluded_paths, debug, wasm):
     """Return a list of `RefTestCase` objects for the jsshell testharness.js
     tests filtered by the given paths and debug-ness."""
     repo_root = abspath(os.path.join(here, "..", "..", ".."))
@@ -340,6 +340,7 @@ def load_wpt_tests(requested_paths, excluded_paths, debug):
         "metadata_root": os.path.join(wp, "meta"),
         "gecko_e10s": False,
         "verify": False,
+        "wasm": wasm,
     }
     wptcommandline.set_from_config(kwargs)
     test_paths = kwargs["test_paths"]
diff --git a/testing/web-platform/tests/tools/wptrunner/wptrunner/browsers/firefox.py b/testing/web-platform/tests/tools/wptrunner/wptrunner/browsers/firefox.py
index 14813b55fd5f..04f2ce84a416 100644
--- a/testing/web-platform/tests/tools/wptrunner/wptrunner/browsers/firefox.py
+++ b/testing/web-platform/tests/tools/wptrunner/wptrunner/browsers/firefox.py
@@ -136,6 +136,7 @@ def env_options():
 
 def run_info_extras(**kwargs):
     return {"e10s": kwargs["gecko_e10s"],
+            "wasm": kwargs.get("wasm", True),
             "verify": kwargs["verify"],
             "headless": "MOZ_HEADLESS" in os.environ}