diff --git a/src/lib/strings/url-helpers.ts b/src/lib/strings/url-helpers.ts
index 08ecf4b566..6a4e3335f8 100644
--- a/src/lib/strings/url-helpers.ts
+++ b/src/lib/strings/url-helpers.ts
@@ -27,6 +27,15 @@ const TRUSTED_REGEX = new RegExp(
   )})|/|#)`,
 )
 
+export function canParseUrl(url: string | URL, base?: string | URL): boolean {
+  try {
+    new URL(url, base)
+    return true
+  } catch {
+    return false
+  }
+}
+
 export function isValidDomain(str: string): boolean {
   return !!TLDs.find(tld => {
     let i = str.lastIndexOf(tld)
diff --git a/src/state/session/session-core.ts b/src/state/session/session-core.ts
index cce2a0e2d5..dbed9bfa2f 100644
--- a/src/state/session/session-core.ts
+++ b/src/state/session/session-core.ts
@@ -6,6 +6,7 @@ import {
 } from '@atproto/lex-password-session'
 
 import {PUBLIC_BSKY_SERVICE} from '#/lib/constants'
+import {canParseUrl} from '#/lib/strings/url-helpers'
 import {logger} from '#/logger'
 import {prefetchAgeAssuranceServerData} from '#/ageAssurance/data'
 import {features} from '#/analytics'
@@ -102,7 +103,7 @@ export function buildBundle(
    * and let the session route against its own service instead.
    */
   const agent =
-    storedPdsUrl && URL.canParse(storedPdsUrl)
+    storedPdsUrl && canParseUrl(storedPdsUrl)
       ? routeSessionToPds(session, storedPdsUrl)
       : session
   return {