diff --git a/js/cookieContentBlocker.js b/js/cookieContentBlocker.js
index d86ad7f..ae5eee5 100644
--- a/js/cookieContentBlocker.js
+++ b/js/cookieContentBlocker.js
@@ -46,12 +46,21 @@
    *   Whether or not we have a cookie value match.
    */
   var matchCookieValue = function (cookieMatch) {
+    // Make sure the name of the cookie and the value to compare against is set.
+    if (typeof cookieMatch.name !== 'string' && typeof cookieMatch.value !== 'string') {
+      return false;
+    }
+
+    // Load the current value of the cookie.
     var currentValue = $.cookie(cookieMatch.name);
 
-    if (currentValue === null || currentValue === void (0) || typeof cookieMatch.value !== 'string') {
-      return false;
+    // Handle special case when the cookie is not set.
+    if (currentValue === null || currentValue === void (0)) {
+      // Handle special case of 'not exists' operator.
+      return cookieMatch.operator === '!e'
     }
 
+    // Create a map for the rest of the operators.
     var matchMap = {
       'e': function () {
         return true;
@@ -67,9 +76,13 @@
       },
       'c': function (v) {
         return currentValue.includes(v);
+      },
+      '!c': function (v) {
+        return !currentValue.includes(v);
       }
     };
 
+    // If the operator is set, do the comparison.
     return (matchMap[cookieMatch.operator] !== void (0) && matchMap[cookieMatch.operator](cookieMatch.value) || false);
   };
 
diff --git a/src/Form/BlockerSettingsForm.php b/src/Form/BlockerSettingsForm.php
index 2d20b2d..10872f2 100644
--- a/src/Form/BlockerSettingsForm.php
+++ b/src/Form/BlockerSettingsForm.php
@@ -154,7 +154,9 @@ class BlockerSettingsForm extends ConfigFormBase {
       '>' => $this->t('Greater than'),
       '<' => $this->t('Less than'),
       'c' => $this->t('Contains'),
+      '!c' => $this->t('Not contains'),
       'e' => $this->t('Exists'),
+      '!e' => $this->t('Not exists'),
     ];
   }