diff --git a/django/contrib/admin/templatetags/admin_list.py b/django/contrib/admin/templatetags/admin_list.py
index 29b5d71a161..0f15781fa94 100644
--- a/django/contrib/admin/templatetags/admin_list.py
+++ b/django/contrib/admin/templatetags/admin_list.py
@@ -31,7 +31,7 @@ def paginator_number(cl,i):
     if i == DOT:
         return '... '
     elif i == cl.page_num:
-        return format_html('<span class="this-page">{}</span> ', i+1)
+        return format_html('<span class="this-page">{0}</span> ', i+1)
     else:
         return format_html('<a href="{0}"{1}>{2}</a> ',
                            cl.get_query_string({PAGE_VAR: i}),
@@ -162,7 +162,7 @@ def result_headers(cl):
             "url_primary": cl.get_query_string({ORDER_VAR: '.'.join(o_list_primary)}),
             "url_remove": cl.get_query_string({ORDER_VAR: '.'.join(o_list_remove)}),
             "url_toggle": cl.get_query_string({ORDER_VAR: '.'.join(o_list_toggle)}),
-            "class_attrib": format_html(' class="{}"', ' '.join(th_classes))
+            "class_attrib": format_html(' class="{0}"', ' '.join(th_classes))
                             if th_classes else '',
         }
 
diff --git a/django/forms/forms.py b/django/forms/forms.py
index 880873a273a..79422756098 100644
--- a/django/forms/forms.py
+++ b/django/forms/forms.py
@@ -167,7 +167,7 @@ class BaseForm(StrAndUnicode):
                     # punctuation.
                     if self.label_suffix:
                         if label[-1] not in ':?.!':
-                            label = format_html('{}{}', label, self.label_suffix)
+                            label = format_html('{0}{1}', label, self.label_suffix)
                     label = bf.label_tag(label) or ''
                 else:
                     label = ''
diff --git a/django/forms/util.py b/django/forms/util.py
index 91a5686886e..8cf03d38aff 100644
--- a/django/forms/util.py
+++ b/django/forms/util.py
@@ -20,7 +20,7 @@ def flatatt(attrs):
 
     The result is passed through 'mark_safe'.
     """
-    return format_html_join('', ' {}="{}"', attrs.items())
+    return format_html_join('', ' {0}="{1}"', attrs.items())
 
 class ErrorDict(dict, StrAndUnicode):
     """
@@ -33,7 +33,7 @@ class ErrorDict(dict, StrAndUnicode):
 
     def as_ul(self):
         if not self: return ''
-        return format_html('<ul class="errorlist">{}</ul>',
+        return format_html('<ul class="errorlist">{0}</ul>',
                            format_html_join('', '<li>{0}{1}</li>',
                                             ((k, force_unicode(v))
                                              for k, v in self.items())
@@ -51,8 +51,8 @@ class ErrorList(list, StrAndUnicode):
 
     def as_ul(self):
         if not self: return ''
-        return format_html('<ul class="errorlist">{}</ul>',
-                           format_html_join('', '<li>{}</li>',
+        return format_html('<ul class="errorlist">{0}</ul>',
+                           format_html_join('', '<li>{0}</li>',
                                             ((force_unicode(e),) for e in self)
                                             )
                            )
diff --git a/django/forms/widgets.py b/django/forms/widgets.py
index 65caa68db2d..04a838093c7 100644
--- a/django/forms/widgets.py
+++ b/django/forms/widgets.py
@@ -254,7 +254,7 @@ class Input(Widget):
         if value != '':
             # Only add the 'value' attribute if a value is non-empty.
             final_attrs['value'] = force_unicode(self._format_value(value))
-        return format_html('<input{} />', flatatt(final_attrs))
+        return format_html('<input{0} />', flatatt(final_attrs))
 
 class TextInput(Input):
     input_type = 'text'
@@ -295,7 +295,7 @@ class MultipleHiddenInput(HiddenInput):
                 # An ID attribute was given. Add a numeric index as a suffix
                 # so that the inputs don't all have the same ID attribute.
                 input_attrs['id'] = '%s_%s' % (id_, i)
-            inputs.append(format_html('<input{} />', flatatt(input_attrs)))
+            inputs.append(format_html('<input{0} />', flatatt(input_attrs)))
         return mark_safe('\n'.join(inputs))
 
     def value_from_datadict(self, data, files, name):
@@ -512,7 +512,7 @@ class CheckboxInput(Widget):
         if not (value is True or value is False or value is None or value == ''):
             # Only add the 'value' attribute if a value is non-empty.
             final_attrs['value'] = force_unicode(value)
-        return format_html('<input{} />', flatatt(final_attrs))
+        return format_html('<input{0} />', flatatt(final_attrs))
 
     def value_from_datadict(self, data, files, name):
         if name not in data:
@@ -544,7 +544,7 @@ class Select(Widget):
     def render(self, name, value, attrs=None, choices=()):
         if value is None: value = ''
         final_attrs = self.build_attrs(attrs, name=name)
-        output = [format_html('<select{}>', flatatt(final_attrs))]
+        output = [format_html('<select{0}>', flatatt(final_attrs))]
         options = self.render_options(choices, [value])
         if options:
             output.append(options)
@@ -620,7 +620,7 @@ class SelectMultiple(Select):
     def render(self, name, value, attrs=None, choices=()):
         if value is None: value = []
         final_attrs = self.build_attrs(attrs, name=name)
-        output = [format_html('<select multiple="multiple"{}>', flatatt(final_attrs))]
+        output = [format_html('<select multiple="multiple"{0}>', flatatt(final_attrs))]
         options = self.render_options(choices, value)
         if options:
             output.append(options)
@@ -679,7 +679,7 @@ class RadioInput(SubWidget):
         final_attrs = dict(self.attrs, type='radio', name=self.name, value=self.choice_value)
         if self.is_checked():
             final_attrs['checked'] = 'checked'
-        return format_html('<input{} />', flatatt(final_attrs))
+        return format_html('<input{0} />', flatatt(final_attrs))
 
 class RadioFieldRenderer(StrAndUnicode):
     """
diff --git a/django/template/defaulttags.py b/django/template/defaulttags.py
index d27439b3b87..52d886a5a11 100644
--- a/django/template/defaulttags.py
+++ b/django/template/defaulttags.py
@@ -47,7 +47,7 @@ class CsrfTokenNode(Node):
             if csrf_token == 'NOTPROVIDED':
                 return format_html("")
             else:
-                return format_html("<div style='display:none'><input type='hidden' name='csrfmiddlewaretoken' value='{}' /></div>", csrf_token)
+                return format_html("<div style='display:none'><input type='hidden' name='csrfmiddlewaretoken' value='{0}' /></div>", csrf_token)
         else:
             # It's very probable that the token is missing because of
             # misconfiguration, so we raise a warning