diff --git a/.env.example b/.env.example
index ddd82a4..549f753 100644
--- a/.env.example
+++ b/.env.example
@@ -5,6 +5,7 @@
 
 NEXT_PUBLIC_SUPABASE_URL=https://your-project-ref.supabase.co
 NEXT_PUBLIC_SUPABASE_ANON_KEY=your-anon-public-key
+NEXT_PUBLIC_SITE_URL=http://localhost:3000
 
 # ---------------------------------------------------------------------------
 # Analytics (optional)
diff --git a/src/app/login/login-form.tsx b/src/app/login/login-form.tsx
index 0bce45c..5d75acc 100644
--- a/src/app/login/login-form.tsx
+++ b/src/app/login/login-form.tsx
@@ -50,10 +50,11 @@ export function LoginForm() {
   }
 
   async function handleGoogle() {
+    const siteUrl = process.env.NEXT_PUBLIC_SITE_URL ?? window.location.origin;
     const { error } = await supabase.auth.signInWithOAuth({
       provider: "google",
       options: {
-        redirectTo: `${window.location.origin}/auth/callback?next=${encodeURIComponent(next)}`,
+        redirectTo: `${siteUrl}/auth/callback?next=${encodeURIComponent(next)}`,
       },
     });
     if (error) toast.error(error.message);