diff --git a/packages/browser/src/utils/hasAuthParamsInUrl.ts b/packages/browser/src/utils/hasAuthParamsInUrl.ts
index 7d2e317b..69a6169c 100644
--- a/packages/browser/src/utils/hasAuthParamsInUrl.ts
+++ b/packages/browser/src/utils/hasAuthParamsInUrl.ts
@@ -17,10 +17,12 @@
  */
 
 /**
- * Utility to check if `code` and `session_state` are available in the URL as search params.
+ * Utility to check if `code` is available in the URL as a search param.
  *
- * @param params - The URL search params to check. Defaults to `window.location.search`.
- * @return `true` if the URL contains `code` and `session_state` search params, otherwise `false`.
+ * @param params - The raw `URL.search` string to check (e.g. `"?code=abc&foo=bar"`). Must include
+ *   the leading `?` or `&` delimiter — do **not** pass a `URLSearchParams.toString()` result, which
+ *   omits the leading `?` and will never match. Defaults to `window.location.search`.
+ * @return `true` if the URL contains a `code` search param, otherwise `false`.
  */
 const hasAuthParamsInUrl = (params: string = window.location.search): boolean => {
   const MATCHER = /[?&]code=[^&]+/;
diff --git a/packages/react/src/hooks/useBrowserUrl.ts b/packages/react/src/hooks/useBrowserUrl.ts
index 58495333..863bf5fa 100644
--- a/packages/react/src/hooks/useBrowserUrl.ts
+++ b/packages/react/src/hooks/useBrowserUrl.ts
@@ -51,6 +51,7 @@ export interface UseBrowserUrl {
  * const { hasAuthParams } = useBrowserUrl();
  * const url = new URL(window.location.href);
  *
+ * // afterSignInUrl may be absolute ("https://example.com/after-signin") or relative ("/after-signin")
  * if (hasAuthParams(url, "/after-signin")) {
  *   // Handle authentication callback
  * }
@@ -58,7 +59,7 @@ export interface UseBrowserUrl {
  */
 const useBrowserUrl = (): UseBrowserUrl => {
   const hasAuthParams = (url: URL, afterSignInUrl: string): boolean =>
-    (hasAuthParamsInUrl() && new URL(url.origin + url.pathname).toString() === new URL(afterSignInUrl).toString()) ||
+    (hasAuthParamsInUrl(url.search) && new URL(url.origin + url.pathname).toString() === new URL(afterSignInUrl, url.origin).toString()) ||
     // authParams?.authorizationCode || // FIXME: These are sent externally. Need to see what we can do about this.
     url.searchParams.get('error') !== null;
 
diff --git a/packages/vue/src/providers/ThunderIDProvider.ts b/packages/vue/src/providers/ThunderIDProvider.ts
index 32f265a6..99ad18ac 100644
--- a/packages/vue/src/providers/ThunderIDProvider.ts
+++ b/packages/vue/src/providers/ThunderIDProvider.ts
@@ -77,7 +77,7 @@ interface ThunderIDProviderProps {
  */
 function hasAuthParams(url: URL, afterSignInUrl: string | undefined): boolean {
   return (
-    (hasAuthParamsInUrl() &&
+    (hasAuthParamsInUrl(url.search) &&
       !!afterSignInUrl &&
       new URL(url.origin + url.pathname).toString() === new URL(afterSignInUrl).toString()) ||
     url.searchParams.get('error') !== null