diff --git a/static/templates/emoji_popover_content.hbs b/static/templates/emoji_popover_content.hbs
index 8a751297ca..6d3efe4b19 100644
--- a/static/templates/emoji_popover_content.hbs
+++ b/static/templates/emoji_popover_content.hbs
@@ -1,6 +1,6 @@
 <div class="emoji-popover">
     <div class="emoji-popover-top input-append">
-        <input class="emoji-popover-filter" type="text" autofocus placeholder={{t 'Search' }} />
+        <input class="emoji-popover-filter" type="text" autofocus placeholder="{{t 'Search' }}" />
         <i class="fa fa-search" aria-hidden="true"></i>
     </div>
     <div class="emoji-popover-category-tabs">
diff --git a/static/templates/emoji_popover_emoji.hbs b/static/templates/emoji_popover_emoji.hbs
index 199e7f8cfd..3d660da870 100644
--- a/static/templates/emoji_popover_emoji.hbs
+++ b/static/templates/emoji_popover_emoji.hbs
@@ -1,5 +1,5 @@
 {{#with emoji_dict}}
-<div class="emoji-popover-emoji {{#if ../message_id }}{{#if has_reacted}} reacted {{/if}} reaction {{else}} composition {{/if}}" data-emoji-name={{name}} tabindex="0" data-emoji-id="{{../type}},{{../section}},{{../index}}">
+<div class="emoji-popover-emoji {{#if ../message_id }}{{#if has_reacted}} reacted {{/if}} reaction {{else}} composition {{/if}}" data-emoji-name="{{name}}" tabindex="0" data-emoji-id="{{../type}},{{../section}},{{../index}}">
     {{#if is_realm_emoji}}
     <img src="{{url}}" class="emoji"/>
     {{else}}
diff --git a/static/templates/input_pill.hbs b/static/templates/input_pill.hbs
index 72068067d7..1e1a249ca2 100644
--- a/static/templates/input_pill.hbs
+++ b/static/templates/input_pill.hbs
@@ -1,6 +1,6 @@
 <div class='pill' data-id='{{ id }}' tabindex=0>
     {{#if has_image}}
-    <img class="pill-image" src={{img_src}} />
+    <img class="pill-image" src="{{img_src}}" />
     {{/if}}
     <span class="pill-value">{{ display_value }}</span>
     <div class="exit">
diff --git a/static/templates/message_reaction.hbs b/static/templates/message_reaction.hbs
index 6fadb7d92b..56776d67f1 100644
--- a/static/templates/message_reaction.hbs
+++ b/static/templates/message_reaction.hbs
@@ -1,4 +1,4 @@
-<div class="{{this.class}}" aria-label="{{this.label}}" data-reaction-id={{this.local_id}}>
+<div class="{{this.class}}" aria-label="{{this.label}}" data-reaction-id="{{this.local_id}}">
     {{#if this.emoji_alt_code}}
         <div class="emoji_alt_code">&nbsp:{{this.emoji_name}}:</div>
     {{else}}
diff --git a/static/templates/muted_topic_ui_row.hbs b/static/templates/muted_topic_ui_row.hbs
index 7a5f09aa08..574b1c6cb3 100644
--- a/static/templates/muted_topic_ui_row.hbs
+++ b/static/templates/muted_topic_ui_row.hbs
@@ -1,5 +1,5 @@
 {{#with muted_topics}}
-<tr data-stream-id={{stream_id}} data-stream="{{stream}}" data-topic="{{topic}}" data-date-muted="{{date_muted_str}}">
+<tr data-stream-id="{{stream_id}}" data-stream="{{stream}}" data-topic="{{topic}}" data-date-muted="{{date_muted_str}}">
     <td>{{stream}}</td>
     <td>{{topic}}</td>
     <td>{{date_muted_str}}</td>
diff --git a/static/templates/settings/notification_settings.hbs b/static/templates/settings/notification_settings.hbs
index 0eb2ab3281..d6ae9b5a95 100644
--- a/static/templates/settings/notification_settings.hbs
+++ b/static/templates/settings/notification_settings.hbs
@@ -76,7 +76,7 @@
                     {{/each}}
                 </select>
                 <span id="play_notification_sound">
-                    <i class="fa fa-play-circle" aria-label={{t "Play sound" }}></i>
+                    <i class="fa fa-play-circle" aria-label="{{t 'Play sound' }}"></i>
                 </span>
             </div>
 
diff --git a/static/templates/user_profile_modal.hbs b/static/templates/user_profile_modal.hbs
index a72038b6bb..210f47dcfd 100644
--- a/static/templates/user_profile_modal.hbs
+++ b/static/templates/user_profile_modal.hbs
@@ -50,9 +50,9 @@
                         <div class="input" contenteditable="false" style="display: none;"></div>
                     </div>
                     {{else if this.is_link}}
-                    <a href={{this.value}} target="_blank" class="value">{{this.value}}</a>
+                    <a href="{{this.value}}" target="_blank" class="value">{{this.value}}</a>
                     {{else if this.is_external_account}}
-                    <a href={{this.link}} target="_blank" class="value">{{this.value}}</a>
+                    <a href="{{this.link}}" target="_blank" class="value">{{this.value}}</a>
                 {{else}}
                     {{#if this.rendered_value}}
                     <div class="value rendered_markdown">{{rendered_markdown this.rendered_value}}</div>
diff --git a/templates/zerver/archive/single_message.html b/templates/zerver/archive/single_message.html
index bdde03a2ca..705d5935a1 100644
--- a/templates/zerver/archive/single_message.html
+++ b/templates/zerver/archive/single_message.html
@@ -5,7 +5,7 @@
       <span class="message_sender{% if status_message %} sender_info_hover{% endif %} no-select">
           {% if include_sender %}
           <div class="inline_profile_picture">
-              <img src={{ avatar_url }} alt="" class="no-drag"/>
+              <img src="{{ avatar_url }}" alt="" class="no-drag"/>
           </div>
               {% if status_message %}
                   <span class="sender-status">
diff --git a/templates/zerver/integrations/index.html b/templates/zerver/integrations/index.html
index f22b58ab1d..dd646c7f4c 100644
--- a/templates/zerver/integrations/index.html
+++ b/templates/zerver/integrations/index.html
@@ -144,7 +144,7 @@
 
                     {% for integration in integrations_dict.values() %}
                         {% if integration.is_enabled() %}
-                        <div id={{ integration.name }} class="integration-instructions">
+                        <div id="{{ integration.name }}" class="integration-instructions">
                             <div class="help-content"></div>
                             <p style="font-size:11px; font-style:italic;">
                                 Logos are trademarks of their respective owners.
diff --git a/templates/zerver/register.html b/templates/zerver/register.html
index 7840bb20ae..6c26010000 100644
--- a/templates/zerver/register.html
+++ b/templates/zerver/register.html
@@ -28,7 +28,7 @@ Form is validated both client-side using jquery-validate (see signup.js) and ser
                         <input id="id_team_name" class="required" type="text"
                           placeholder="Acme or Ακμή"
                           value="{% if form.realm_name.value() %}{{ form.realm_name.value() }}{% endif %}"
-                          name="realm_name" maxlength={{ MAX_REALM_NAME_LENGTH }} required />
+                          name="realm_name" maxlength="{{ MAX_REALM_NAME_LENGTH }}" required />
                     </div>
                     <label for="id_team_name" class="inline-block label-title">{{ _('Organization name') }}</label>
                     {% if form.realm_name.errors %}
@@ -63,7 +63,7 @@ Form is validated both client-side using jquery-validate (see signup.js) and ser
                               class="{% if root_domain_landing_page %}required{% endif %} subdomain" type="text"
                               placeholder="acme"
                               value="{% if form.realm_subdomain.value() %}{{ form.realm_subdomain.value() }}{% endif %}"
-                              name="realm_subdomain" maxlength={{ MAX_REALM_SUBDOMAIN_LENGTH }}
+                              name="realm_subdomain" maxlength="{{ MAX_REALM_SUBDOMAIN_LENGTH }}"
                               {% if root_domain_landing_page %}required{% endif %} />
                             <label for="id_team_subdomain" class="realm_subdomain_label">.{{ external_host }}</label>
                             <p id="id_team_subdomain_error_client" class="error help-inline text-error"></p>
@@ -124,7 +124,7 @@ Form is validated both client-side using jquery-validate (see signup.js) and ser
                     {% else %}
                         <input id="id_full_name" class="required" type="text" name="full_name"
                           value="{% if full_name %}{{ full_name }}{% elif form.full_name.value() %}{{ form.full_name.value() }}{% endif %}"
-                          maxlength={{ MAX_NAME_LENGTH }} placeholder="{% trans %}Full name or 名前{% endtrans %}" required />
+                          maxlength="{{ MAX_NAME_LENGTH }}" placeholder="{% trans %}Full name or 名前{% endtrans %}" required />
                         <label for="id_full_name" class="inline-block label-title">{{ _('Full name') }}</label>
                         {% if form.full_name.errors %}
                             {% for error in form.full_name.errors %}
@@ -151,7 +151,7 @@ Form is validated both client-side using jquery-validate (see signup.js) and ser
                 <div class="input-box">
                     <input id="id_password" class="required" type="password" name="password"
                       value="{% if form.password.value() %}{{ form.password.value() }}{% endif %}"
-                      maxlength={{ MAX_PASSWORD_LENGTH }}
+                      maxlength="{{ MAX_PASSWORD_LENGTH }}"
                       data-min-length="{{password_min_length}}"
                       data-min-guesses="{{password_min_guesses}}" required />
                     <label for="id_password" class="inline-block">{{ _('Password') }}</label>
diff --git a/tools/linter_lib/custom_check.py b/tools/linter_lib/custom_check.py
index 59e7896d78..69a64db2bd 100644
--- a/tools/linter_lib/custom_check.py
+++ b/tools/linter_lib/custom_check.py
@@ -498,6 +498,12 @@ html_rules: List["Rule"] = whitespace_rules + prose_style_rules + [
      'exclude': {"templates/analytics/support.html"},
      'good_lines': ['<input class="stream-list-filter" type="text" placeholder="{{ _(\'Search streams\') }}" />'],
      'bad_lines': ['<input placeholder="foo">']},
+    {'pattern': '={',
+     # TODO: Improve the Apple auth patterns so we can remove this.
+     'exclude_pattern': 'appleid.cdn-apple.com/appleid/button',
+     'description': "Likely missing quoting in HTML attribute",
+     'good_lines': ['<a href="{{variable}}">'],
+     'bad_lines': ['<a href={{variable}}>']},
     {'pattern': "placeholder='[^{]",
      'description': "`placeholder` value should be translatable.",
      'good_lines': ['<input class="stream-list-filter" type="text" placeholder="{{ _(\'Search streams\') }}" />'],