diff --git a/document/web-api/index.bs b/document/web-api/index.bs
index 0c0c67d3e1..83d8288d81 100644
--- a/document/web-api/index.bs
+++ b/document/web-api/index.bs
@@ -88,9 +88,9 @@ additional APIs that are implemented by Web user agents but are outside the scop
 <pre class="idl">
 [Exposed=(Window,Worker)]
 partial namespace WebAssembly {
-  Promise&lt;Module> compileStreaming(Promise&lt;Response> source, optional WebAssemblyCompileOptions options);
+  Promise&lt;Module> compileStreaming(Promise&lt;Response> source, optional WebAssemblyCompileOptions options = {});
   Promise&lt;WebAssemblyInstantiatedSource> instantiateStreaming(
-      Promise&lt;Response> source, optional object importObject, optional WebAssemblyCompileOptions options);
+      Promise&lt;Response> source, optional object importObject, optional WebAssemblyCompileOptions options = {});
 };
 </pre>