diff --git a/apps/web/src/views/partials/monitor-form-js.ejs b/apps/web/src/views/partials/monitor-form-js.ejs
index 44c4ffe..33d4aae 100644
--- a/apps/web/src/views/partials/monitor-form-js.ejs
+++ b/apps/web/src/views/partials/monitor-form-js.ejs
@@ -49,6 +49,7 @@
       const rb = document.getElementById(prefix + 'request-body').value.trim();
       body.request_body = rb || null;
       body.regions = [...document.querySelectorAll('.' + prefix + 'region-check:checked')].map(el => el.value);
+      if (!body.regions.length) throw new Error('Select at least one region');
       if (_currentQuery) body.query = _currentQuery;
       return body;
     }
diff --git a/apps/web/src/views/partials/monitor-form.ejs b/apps/web/src/views/partials/monitor-form.ejs
index e2572f1..c34ee73 100644
--- a/apps/web/src/views/partials/monitor-form.ejs
+++ b/apps/web/src/views/partials/monitor-form.ejs
@@ -81,12 +81,16 @@
     </div>
   </div>
 
+  <%
+    // Default to eu-central if no regions selected
+    const selectedRegions = (monitor.regions && monitor.regions.length) ? monitor.regions : ['eu-central'];
+  %>
   <div>
-    <label class="block text-sm text-gray-400 mb-1.5">Regions <span class="text-gray-600">(leave all unselected to use all regions)</span></label>
+    <label class="block text-sm text-gray-400 mb-1.5">Regions</label>
     <div class="flex flex-wrap gap-2">
       <% regions.forEach(function([val, label]) { %>
       <label class="flex items-center gap-2 <%= bg %> border <%= border %> hover:border-gray-600 rounded-lg px-3 py-2 cursor-pointer transition-colors">
-        <input type="checkbox" value="<%= val %>" class="<%= prefix %>region-check accent-blue-500" <%= (monitor.regions && monitor.regions.includes(val)) ? 'checked' : '' %>> <span class="text-sm text-gray-300"><%~ label %></span>
+        <input type="checkbox" value="<%= val %>" class="<%= prefix %>region-check accent-blue-500" <%= selectedRegions.includes(val) ? 'checked' : '' %>> <span class="text-sm text-gray-300"><%~ label %></span>
       </label>
       <% }) %>
     </div>