diff --git a/spec.bs b/spec.bs
index adfd67c..27c3a57 100644
--- a/spec.bs
+++ b/spec.bs
@@ -18,6 +18,9 @@ spec: ECMASCRIPT; urlPrefix: https://tc39.es/ecma262/
   type: dfn
     text: IdentifierPart; url: #prod-IdentifierPart
     text: IdentifierStart; url: #prod-IdentifierStart
+spec: URL; urlPrefix: https://url.spec.whatwg.org/
+  type: dfn
+    text: serialize an integer; url: #serialize-an-integer
 </pre>
 
 <h2 id=urlpattern-class>The {{URLPattern}} class</h2>
@@ -1737,7 +1740,7 @@ To <dfn>convert a modifier to a string</dfn> given a [=part/modifier=] |modifier
      <p class="note">Note, we set the [=URL record=]'s [=url/scheme=] in order for the [=basic URL parser=] to recognize and normalize default port values.</p>
   1. Let |parseResult| be the result of running [=basic URL parser=] given |portValue| with |dummyURL| as <i>[=basic URL parser/url=]</i> and [=port state=] as <i>[=basic URL parser/state override=]</i>.
   1. If |parseResult| is failure, then throw a {{TypeError}}.
-  1. Return |dummyURL|'s [=url/port=] or empty string if it is null.
+  1. Return |dummyURL|'s [=url/port=], [=serialize an integer|serialized=], or empty string if it is null.
 </div>
 
 <div algorithm>
@@ -1823,11 +1826,22 @@ To <dfn>convert a modifier to a string</dfn> given a [=part/modifier=] |modifier
     1. If |init|["{{URLPatternInit/protocol}}"] does not [=map/exist=], then set |result|["{{URLPatternInit/protocol}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/scheme=] and |type|.
     1. If |type| is not "`pattern`" and |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}" and "{{URLPatternInit/username}}", then set |result|["{{URLPatternInit/username}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/username=] and |type|.
     1. If |type| is not "`pattern`" and |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/username}}" and "{{URLPatternInit/password}}", then set |result|["{{URLPatternInit/password}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/password=] and |type|.
-    1. If |init| [=map/contains=] neither "{{URLPatternInit/protocol}}" nor "{{URLPatternInit/hostname}}", then set |result|["{{URLPatternInit/hostname}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/host=] and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", and "{{URLPatternInit/port}}", then set |result|["{{URLPatternInit/port}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/port=] and |type|.
+    1. If |init| [=map/contains=] neither "{{URLPatternInit/protocol}}" nor "{{URLPatternInit/hostname}}", then:
+      1. Let |baseHost| be |baseURL|'s [=url/host=].
+      1. If |baseHost| is null, then set |baseHost| to the empty string.
+      1. Set |result|["{{URLPatternInit/hostname}}"] to the result of [=processing a base URL string=] given |baseHost| and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", and "{{URLPatternInit/port}}", then:
+      1. If |baseURL|'s [=url/port=] is null, then set |result|["{{URLPatternInit/port}}"] to the empty string.
+      1. Otherwise, set |result|["{{URLPatternInit/port}}"] to |baseURL|'s [=url/port=], [=serialize an integer|serialized=].
     1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", and "{{URLPatternInit/pathname}}", then set |result|["{{URLPatternInit/pathname}}"] to the result of [=processing a base URL string=] given the result of [=URL path serializing=] |baseURL| and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", and "{{URLPatternInit/search}}", then set |result|["{{URLPatternInit/search}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/query=] and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", "{{URLPatternInit/search}}", and "{{URLPatternInit/hash}}", then set |result|["{{URLPatternInit/hash}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/fragment=] and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", and "{{URLPatternInit/search}}", then:
+      1. Let |baseQuery| be |baseURL|'s [=url/query=].
+      1. If |baseQuery| is null, then set |baseQuery| to the empty string.
+      1. Set |result|["{{URLPatternInit/search}}"] to the result of [=processing a base URL string=] given |baseQuery| and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", "{{URLPatternInit/search}}", and "{{URLPatternInit/hash}}", then:
+      1. Let |baseFragment| be |baseURL|'s [=url/fragment=].
+      1. If |baseFragment| is null, then set |baseFragment| to the empty string.
+      1. Set |result|["{{URLPatternInit/hash}}"] to the result of [=processing a base URL string=] given |baseFragment| and |type|.
   1. If |init|["{{URLPatternInit/protocol}}"] [=map/exists=], then set |result|["{{URLPatternInit/protocol}}"] to the result of [=process protocol for init=] given |init|["{{URLPatternInit/protocol}}"] and |type|.
   1. If |init|["{{URLPatternInit/username}}"] [=map/exists=], then set |result|["{{URLPatternInit/username}}"] to the result of [=process username for init=] given |init|["{{URLPatternInit/username}}"] and |type|.
   1. If |init|["{{URLPatternInit/password}}"] [=map/exists=], then set |result|["{{URLPatternInit/password}}"] to the result of [=process password for init=] given |init|["{{URLPatternInit/password}}"] and |type|.