diff --git a/src/lib/url_util.test.ts b/src/lib/url_util.test.ts
index 4da29669..fb675d10 100644
--- a/src/lib/url_util.test.ts
+++ b/src/lib/url_util.test.ts
@@ -347,6 +347,21 @@ function test_url_graft_path() {
 function test_url_query_interpolation() {
     let cases = [
         ["http://example.com/%s000", "a/query", "http://example.com/a%2Fquery000"],
+        [
+            "https://%s1.wikipedia.org/wiki/%s2",
+            "en Tridactyl",
+            "https://en.wikipedia.org/wiki/Tridactyl",
+        ],
+        [
+            "https://%s.wikipedia.org/wiki/Tridactyl",
+            "en",
+            "https://en.wikipedia.org/wiki/Tridactyl",
+        ],
+        [
+            "https://%s[1:2].wikipedia.org/wiki/%s[2:]",
+            "en Main Page",
+            "https://en.wikipedia.org/wiki/Main%20Page",
+        ],
         [
             // appended to the path
             "http://example.com",
@@ -384,7 +399,7 @@ function test_url_query_interpolation() {
     ]
 
     for (let [url, qy, exp_res] of cases) {
-        let modified = UrlUtil.interpolateSearchItem(new URL(url), qy)
+        let modified = UrlUtil.interpolateSearchItem(url, qy)
 
         test(`interpolate ${qy} into ${url} --> ${exp_res}`, () =>
             expect(modified.href).toEqual(exp_res))
@@ -396,7 +411,7 @@ test.each([
     ["wiki", "https://example.com/wiki/", "an/article"],
 ])("convert an interpolated %s URL back to arguments", (engine, pattern, query) => {
     const searchurls = { [engine]: pattern }
-    const url = UrlUtil.interpolateSearchItem(new URL(pattern), query).href
+    const url = UrlUtil.interpolateSearchItem(pattern, query).href
     expect(UrlUtil.searchUrlToArgs(url, searchurls)).toEqual(`${engine} ${query}`)
 })
 
diff --git a/src/lib/url_util.ts b/src/lib/url_util.ts
index 1150c365..0993c87e 100644
--- a/src/lib/url_util.ts
+++ b/src/lib/url_util.ts
@@ -441,14 +441,14 @@ export function searchUrlToArgs(
  *
  * The search item is percent encoded before it is inserted.
  *
- * @param urlPattern        a URL to interpolate/append a query to
+ * @param urlPattern        a URL template to interpolate/append a query to
  * @param query             a query to interpolate/append into the URL
  *
  * @return                  the URL with the query encoded and inserted at the
  *                          relevant point
  */
-export function interpolateSearchItem(urlPattern: URL, query: string): URL {
-    const hasInterpolationPoint = urlPattern.href.includes("%s")
+export function interpolateSearchItem(urlPattern: string, query: string): URL {
+    const hasInterpolationPoint = urlPattern.includes("%s")
 
     let queryWords = query.split(" ")
 
@@ -456,10 +456,10 @@ export function interpolateSearchItem(urlPattern: URL, query: string): URL {
     query = encodeURIComponent(query)
     queryWords = queryWords.map(w => encodeURIComponent(w))
 
-    // replace or append as needed
+    // Interpolate before parsing so placeholders can appear in the hostname.
     if (hasInterpolationPoint) {
-        const resultingURL = new URL(
-            urlPattern.href
+        return new URL(
+            urlPattern
                 .replace(/%s[1-9]\d*/g, function (x) {
                     const index = parseInt(x.slice(2), 10) - 1
                     if (index >= queryWords.length) {
@@ -476,12 +476,11 @@ export function interpolateSearchItem(urlPattern: URL, query: string): URL {
                         ? queryWords.slice(start, l(parseInt(p2, 10)))
                         : queryWords.slice(start)
                     return slice.join(" ")
-                }),
+                })
+                .replace("%s", query),
         )
-
-        return new URL(resultingURL.href.replace("%s", query))
     } else {
-        return new URL(urlPattern.href + query)
+        return new URL(new URL(urlPattern).href + query)
     }
 }
 
diff --git a/src/lib/webext.ts b/src/lib/webext.ts
index c038703c..297fba0d 100644
--- a/src/lib/webext.ts
+++ b/src/lib/webext.ts
@@ -389,7 +389,7 @@ export async function queryAndURLwrangler(
     const searchurls = config.get("searchurls")
     const template = expandRecursively(firstWord, searchurls)
     if (template != firstWord) {
-        const url = UrlUtil.interpolateSearchItem(new URL(template), rest)
+        const url = UrlUtil.interpolateSearchItem(template, rest)
         // firstWord is a searchurl, so let's use that
         return url.href
     }
@@ -445,7 +445,7 @@ export async function queryAndURLwrangler(
     if (enginename) {
         if (searchurls[enginename]) {
             const url = UrlUtil.interpolateSearchItem(
-                new URL(searchurls[enginename]),
+                searchurls[enginename],
                 queryString,
             )
             return url.href