diff --git a/hc/api/models.py b/hc/api/models.py
index 15c0e65e..55fe33e0 100644
--- a/hc/api/models.py
+++ b/hc/api/models.py
@@ -601,13 +601,12 @@ class Channel(models.Model):
         message = f"Challenge token: {challenge}"
         hostname = socket.gethostname()
         submit_url = settings.SITE_ROOT + reverse("hc-signal-captcha")
-        submit_url += urlencode({"host": hostname, "challenge": challenge})
+        submit_url += "?" + urlencode({"host": hostname, "challenge": challenge})
         html_message = f"""
             On host <b>{hostname}</b>, run:<br>
             <pre>manage.py submitchallenge {challenge} CAPTCHA-SOLUTION-HERE</pre><br>
             <br>
-            Alternatively, submit CAPTCHA solution here: <br>
-            {submit_url}<br>
+            Alternatively, <a href="{submit_url}">submit CAPTCHA solution here</a>.<br>
             <br>
             Message from Signal:<br>
             <pre>{raw}</pre>
diff --git a/templates/front/signal_captcha.html b/templates/front/signal_captcha.html
index a10e469f..9f2fa915 100644
--- a/templates/front/signal_captcha.html
+++ b/templates/front/signal_captcha.html
@@ -20,8 +20,9 @@
         <form method="post">
             {% csrf_token %}
             <div class="form-group">
-                <label for="captcha">Challenge</label>
+                <label for="challenge">Challenge</label>
                 <input
+                    id="challenge"
                     name="challenge"
                     required
                     class="form-control"