diff --git a/combo/public/templates/combo/placeholder.html b/combo/public/templates/combo/placeholder.html
index 1c6ddf21..71830a13 100644
--- a/combo/public/templates/combo/placeholder.html
+++ b/combo/public/templates/combo/placeholder.html
@@ -2,7 +2,7 @@
 {% if render %}
 {% for cell in cells %}
 <div class="cell {{ cell.css_class_names }} {% if cell.slug %}{{cell.slug}}{% endif %} {% if cell|shown_because_admin:request %}shown-because-admin{% endif %}"
-     {% if cell.slug %}id="{{ cell.slug }}"{% endif %}
+     {% if cell.slug and cell.use_slug_as_id %}id="{{ cell.slug }}"{% endif %}
      data-ajax-cell-url="{{ site_base }}{% url 'combo-public-ajax-page-cell' page_pk=cell.page.id cell_reference=cell.get_reference %}"
      data-ajax-cell-loading-message="{{ cell.loading_message }}"
      {% if cell.ajax_refresh %}data-ajax-cell-refresh="{{ cell.ajax_refresh }}"{% endif %}
diff --git a/combo/public/views.py b/combo/public/views.py
index ef28caa6..9089e846 100644
--- a/combo/public/views.py
+++ b/combo/public/views.py
@@ -461,9 +461,20 @@ def publish_page(request, page, status=200, template_name=None):
     extend_with_parent_cells(cells, hierarchy=pages)
     cells = [x for x in cells if x.is_visible(user=request.user)]
 
+    # mark duplicated slugs to avoid using them in HTML id attributes.
+    cell_by_slugs = {}
+    for cell in cells:
+        if cell.slug not in cell_by_slugs:
+            cell_by_slugs[cell.slug] = []
+        cell_by_slugs[cell.slug].append(cell)
+    for slug, slug_cells in cell_by_slugs.items():
+        for cell in slug_cells:
+            cell.use_slug_as_id = bool(len(slug_cells) == 1)
+
     ctx = {
         'check_badges': should_check_badges(),
         'page': page,
+        'xxx': 'TOTO',
         'page_cells': cells,
         'pages': pages,
         'request': request,
diff --git a/tests/test_public.py b/tests/test_public.py
index 6574be90..1ba02b38 100644
--- a/tests/test_public.py
+++ b/tests/test_public.py
@@ -868,3 +868,17 @@ def test_sub_slug(app, john_doe, jane_doe):
             # unknown name id => no selected_user
             resp = app.get('/users/foo/', status=200)
             assert 'XXYY' in resp.text
+
+def test_cell_slugs(app):
+    Page.objects.all().delete()
+    page = Page(title='Home', slug='index', template_name='standard')
+    page.save()
+
+    TextCell(page=page, placeholder='content', text='Foobar', order=0).save()
+    TextCell(page=page, placeholder='content', text='Foobar', slug='unique', order=1).save()
+    TextCell(page=page, placeholder='content', text='Foobar', slug='dup', order=2).save()
+    TextCell(page=page, placeholder='content', text='Foobar', slug='dup', order=3).save()
+
+    resp = app.get('/', status=200)
+    assert 'id="unique"' in resp.text
+    assert 'id="dup"' not in resp.text