diff --git a/material/partials/nav-item.html b/material/partials/nav-item.html
index f55ca979f..c1a24a1a0 100644
--- a/material/partials/nav-item.html
+++ b/material/partials/nav-item.html
@@ -40,10 +40,10 @@
       {% set toc = page.toc %}
       <input class="md-nav__toggle md-toggle" data-md-toggle="toc" type="checkbox" id="__toc">
       {% set first = toc | first %}
-      {% if first is defined and first.level == 1 %}
+      {% if first and first.level == 1 %}
         {% set toc = first.children %}
       {% endif %}
-      {% if toc is iterable %}
+      {% if toc %}
         <label class="md-nav__link md-nav__link--active" for="__toc">
           {{ nav_item.title }}
           <span class="md-nav__icon md-icon"></span>
@@ -52,7 +52,7 @@
       <a href="{{ nav_item.url | url }}" class="md-nav__link md-nav__link--active">
         {{ nav_item.title }}
       </a>
-      {% if toc is iterable %}
+      {% if toc %}
         {% include "partials/toc.html" %}
       {% endif %}
     </li>
diff --git a/material/partials/toc.html b/material/partials/toc.html
index 3415ad47c..f28c49f2b 100644
--- a/material/partials/toc.html
+++ b/material/partials/toc.html
@@ -5,10 +5,10 @@
 <nav class="md-nav md-nav--secondary" aria-label="{{ lang.t('toc.title') }}">
   {% set toc = page.toc %}
   {% set first = toc | first %}
-  {% if first is defined and first.level == 1 %}
+  {% if first and first.level == 1 %}
     {% set toc = first.children %}
   {% endif %}
-  {% if toc is iterable %}
+  {% if toc %}
     <label class="md-nav__title" for="__toc">
       <span class="md-nav__icon md-icon"></span>
       {{ lang.t("toc.title") }}
diff --git a/src/partials/nav-item.html b/src/partials/nav-item.html
index b68ee21c4..26a13d7b1 100644
--- a/src/partials/nav-item.html
+++ b/src/partials/nav-item.html
@@ -102,12 +102,12 @@
 
       <!-- Hack: see partials/toc.html for more information -->
       {% set first = toc | first %}
-      {% if first is defined and first.level == 1 %}
+      {% if first and first.level == 1 %}
         {% set toc = first.children %}
       {% endif %}
 
       <!-- Render table of contents, if not empty -->
-      {% if toc is iterable %}
+      {% if toc %}
         <label class="md-nav__link md-nav__link--active" for="__toc">
           {{ nav_item.title }}
           <span class="md-nav__icon md-icon"></span>
@@ -121,7 +121,7 @@
       </a>
 
       <!-- Show table of contents -->
-      {% if toc is iterable %}
+      {% if toc %}
         {% include "partials/toc.html" %}
       {% endif %}
     </li>
diff --git a/src/partials/toc.html b/src/partials/toc.html
index 48afdcfa1..c4c6d7354 100644
--- a/src/partials/toc.html
+++ b/src/partials/toc.html
@@ -33,12 +33,12 @@
     directly continue with the children of the anchor.
   -->
   {% set first = toc | first %}
-  {% if first is defined and first.level == 1 %}
+  {% if first and first.level == 1 %}
     {% set toc = first.children %}
   {% endif %}
 
   <!-- Render item list -->
-  {% if toc is iterable %}
+  {% if toc %}
     <label class="md-nav__title" for="__toc">
       <span class="md-nav__icon md-icon"></span>
       {{ lang.t("toc.title") }}