diff --git a/hc/front/tests/test_my_checks.py b/hc/front/tests/test_my_checks.py
index 5f449cd6..99975c43 100644
--- a/hc/front/tests/test_my_checks.py
+++ b/hc/front/tests/test_my_checks.py
@@ -8,15 +8,17 @@ class MyChecksTestCase(BaseTestCase):
     def setUp(self):
         super().setUp()
         self.check = Check(project=self.project, name="Alice Was Here")
+        self.check.slug = "alice-was-here"
         self.check.save()
 
-        self.url = "/projects/%s/checks/" % self.project.code
+        self.url = f"/projects/{self.project.code}/checks/"
 
     def test_it_works(self):
         for email in ("alice@example.org", "bob@example.org"):
             self.client.login(username=email, password="password")
             r = self.client.get(self.url)
             self.assertContains(r, "Alice Was Here", status_code=200)
+            self.assertContains(r, str(self.check.code), status_code=200)
             # The pause button:
             self.assertContains(r, "btn btn-default pause", status_code=200)
 
@@ -139,3 +141,32 @@ class MyChecksTestCase(BaseTestCase):
 
         # The pause button:
         self.assertNotContains(r, "btn btn-default pause", status_code=200)
+
+    def test_it_shows_slugs(self):
+        self.project.show_slugs = True
+        self.project.save()
+
+        self.client.login(username="alice@example.org", password="password")
+        r = self.client.get(self.url)
+        self.assertContains(r, "alice-was-here")
+        self.assertNotContains(r, "(not unique)")
+
+    def test_it_shows_not_unique_note(self):
+        self.project.show_slugs = True
+        self.project.save()
+
+        dupe = Check(project=self.project, name="Alice Was Here")
+        dupe.slug = "alice-was-here"
+        dupe.save()
+
+        self.client.login(username="alice@example.org", password="password")
+        r = self.client.get(self.url)
+        self.assertContains(r, "alice-was-here")
+        self.assertContains(r, "(not unique)")
+
+    def test_it_saves_url_format_preference(self):
+        self.client.login(username="alice@example.org", password="password")
+        self.client.get(self.url + "?urls=slug")
+
+        self.project.refresh_from_db()
+        self.assertTrue(self.project.show_slugs)
diff --git a/hc/front/views.py b/hc/front/views.py
index d64d0d07..ef017e3a 100644
--- a/hc/front/views.py
+++ b/hc/front/views.py
@@ -209,6 +209,15 @@ def my_checks(request, code):
             if search not in search_key:
                 hidden_checks.add(check)
 
+    # Figure out which checks have ambiguous ping URLs
+    seen, ambiguous = set(), set()
+    if project.show_slugs:
+        for check in checks:
+            if check.slug and check.slug in seen:
+                ambiguous.add(check.slug)
+            else:
+                seen.add(check.slug)
+
     # Do we need to show the "Last Duration" header?
     show_last_duration = False
     for check in checks:
@@ -231,6 +240,7 @@ def my_checks(request, code):
         "selected_tags": selected_tags,
         "search": search,
         "hidden_checks": hidden_checks,
+        "ambiguous": ambiguous,
         "show_last_duration": show_last_duration,
     }
 
diff --git a/templates/front/my_checks_desktop.html b/templates/front/my_checks_desktop.html
index 7b7b56ec..613f6df4 100644
--- a/templates/front/my_checks_desktop.html
+++ b/templates/front/my_checks_desktop.html
@@ -82,10 +82,13 @@
         </td>
         <td class="hidden-xs hidden-sm url">
             {% if project.show_slugs and not check.slug %}
-            <span class="unavailable">unavailable, set name first</span>
+                <span class="unavailable">unavailable, set name first</span>
             {% else %}
-            <span class="my-checks-url">{{ check.url|format_ping_endpoint }}</span>
-            <button class="copy-link" data-clipboard-text="{{ check.url }}">copy</button>
+                <span class="my-checks-url">{{ check.url|format_ping_endpoint }}</span>
+                {% if project.show_slugs and check.slug in ambiguous %}
+                <small class="text-danger">(not unique)</small>
+                {% endif %}
+                <button class="copy-link" data-clipboard-text="{{ check.url }}">copy</button>
             {% endif %}
         </td>
         <td class="hidden-xs">