diff --git a/css/css-layout-api/constraints-data-sab-failure.https.html b/css/css-layout-api/constraints-data-sab-failure.https.html
index eb652d9a552ed0..c03d35074aa632 100644
--- a/css/css-layout-api/constraints-data-sab-failure.https.html
+++ b/css/css-layout-api/constraints-data-sab-failure.https.html
@@ -35,14 +35,9 @@
     let childFragment = null;
 
     try {
-      // We need SABs to be enabled to properly run this test.
-      if (typeof SharedArrayBuffer !== 'undefined') {
-        childFragment = yield child.layoutNextFragment({
-          data: { sab: new SharedArrayBuffer(4) }
-        });
-      } else {
-        throw Error();
-      }
+      childFragment = yield child.layoutNextFragment({
+        data: { sab: new SharedArrayBuffer(4) }
+      });
     } catch(e) {
       // Success! The structured cloning algorithm should have thrown an error.
       childFragment = yield child.layoutNextFragment({});
diff --git a/css/css-layout-api/fragment-data-sab-failure.https.html b/css/css-layout-api/fragment-data-sab-failure.https.html
index 59a9f835728e76..5d3619b3647df8 100644
--- a/css/css-layout-api/fragment-data-sab-failure.https.html
+++ b/css/css-layout-api/fragment-data-sab-failure.https.html
@@ -34,11 +34,7 @@
   *layout(children, edges, constraints, styleMap) {
     const childFragments = yield children.map(child => child.layoutNextFragment());
 
-    if (typeof SharedArrayBuffer !== 'undefined') {
-      return {autoBlockSize: 0, childFragments, data: {sab: new SharedArrayBuffer(4) }};
-    } else {
-      throw Error();
-    }
+    return {autoBlockSize: 0, childFragments, data: {sab: new SharedArrayBuffer(4) }};
   }
 });
 </script>