diff --git a/filter/emoticon/filter.php b/filter/emoticon/filter.php
index d579bf65b9f..5f5b3ff5dc0 100644
--- a/filter/emoticon/filter.php
+++ b/filter/emoticon/filter.php
@@ -32,6 +32,22 @@ defined('MOODLE_INTERNAL') || die();
 
 class filter_emoticon extends moodle_text_filter {
 
+    /**
+     * Internal cache used for replacing. Multidimensional array;
+     * - dimension 1: language,
+     * - dimension 2: theme.
+     * @var array
+     */
+    protected static $emoticontexts = array();
+
+    /**
+     * Internal cache used for replacing. Multidimensional array;
+     * - dimension 1: language,
+     * - dimension 2: theme.
+     * @var array
+     */
+    protected static $emoticonimgs = array();
+
     /**
      * Apply the filter to the text
      *
@@ -49,7 +65,7 @@ class filter_emoticon extends moodle_text_filter {
             return $text;
         }
         if (in_array($options['originalformat'], explode(',', get_config('filter_emoticon', 'formats')))) {
-            $this->replace_emoticons($text);
+            return $this->replace_emoticons($text);
         }
         return $text;
     }
@@ -62,51 +78,73 @@ class filter_emoticon extends moodle_text_filter {
      * Replace emoticons found in the text with their images
      *
      * @param string $text to modify
-     * @return void
+     * @return string the modified result
      */
-    protected function replace_emoticons(&$text) {
+    protected function replace_emoticons($text) {
         global $CFG, $OUTPUT, $PAGE;
-        static $emoticontexts = array();    // internal cache used for replacing
-        static $emoticonimgs = array();     // internal cache used for replacing
 
         $lang = current_language();
         $theme = $PAGE->theme->name;
 
-        if (!isset($emoticontexts[$lang][$theme]) or !isset($emoticonimgs[$lang][$theme])) {
+        if (!isset(self::$emoticontexts[$lang][$theme]) or !isset(self::$emoticonimgs[$lang][$theme])) {
             // prepare internal caches
             $manager = get_emoticon_manager();
             $emoticons = $manager->get_emoticons();
-            $emoticontexts[$lang][$theme] = array();
-            $emoticonimgs[$lang][$theme] = array();
+            self::$emoticontexts[$lang][$theme] = array();
+            self::$emoticonimgs[$lang][$theme] = array();
             foreach ($emoticons as $emoticon) {
-                $emoticontexts[$lang][$theme][] = $emoticon->text;
-                $emoticonimgs[$lang][$theme][] = $OUTPUT->render($manager->prepare_renderable_emoticon($emoticon));
+                self::$emoticontexts[$lang][$theme][] = $emoticon->text;
+                self::$emoticonimgs[$lang][$theme][] = $OUTPUT->render($manager->prepare_renderable_emoticon($emoticon));
             }
             unset($emoticons);
         }
 
-        if (empty($emoticontexts[$lang][$theme])) { // No emoticons defined, nothing to process here
-            return;
+        if (empty(self::$emoticontexts[$lang][$theme])) { // No emoticons defined, nothing to process here.
+            return $text;
         }
 
-        // detect all the <script> zones to take out
-        $excludes = array();
-        preg_match_all('/<script language(.+?)<\/script>/is', $text, $listofexcludes);
+        // Detect all zones that we should not handle (including the nested tags).
+        $processing = preg_split('/(<\/?(?:span|script)[^>]*>)/is', $text, 0, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
 
-        // take out all the <script> zones from text
-        foreach (array_unique($listofexcludes[0]) as $key => $value) {
-            $excludes['<+'.$key.'+>'] = $value;
-        }
-        if ($excludes) {
-            $text = str_replace($excludes, array_keys($excludes), $text);
+        // Initialize the results.
+        $resulthtml = "";
+        $exclude = 0;
+
+        // Define the patterns that mark the start of the forbidden zones.
+        $excludepattern = array('/^<script/is', '/^<span[^>]+class="nolink[^"]*"/is');
+
+        // Loop through the fragments.
+        foreach ($processing as $fragment) {
+            // If we are not ignoring, we MUST test if we should.
+            if ($exclude == 0) {
+                foreach ($excludepattern as $exp) {
+                    if (preg_match($exp, $fragment)) {
+                        $exclude = $exclude + 1;
+                        break;
+                    }
+                }
+            }
+            if ($exclude > 0) {
+                // If we are ignoring the fragment, then we must check if we may have reached the end of the zone.
+                if (strpos($fragment, '</span') !== false || strpos($fragment, '</script') !== false) {
+                    $exclude -= 1;
+                    // This is needed because of a double increment at the first element.
+                    if ($exclude == 1) {
+                        $exclude -= 1;
+                    }
+                } else if (strpos($fragment, '<span') !== false || strpos($fragment, '<script') !== false) {
+                    // If we find a nested tag we increase the exclusion level.
+                    $exclude = $exclude + 1;
+                }
+            } else if (strpos($fragment, '<span') === false ||
+                       strpos($fragment, '</span') === false) {
+                // This is the meat of the code - this is run every time.
+                // This code only runs for fragments that are not ignored (including the tags themselves).
+                $fragment = str_replace(self::$emoticontexts[$lang][$theme], self::$emoticonimgs[$lang][$theme], $fragment);
+            }
+            $resulthtml .= $fragment;
         }
 
-        // this is the meat of the code - this is run every time
-        $text = str_replace($emoticontexts[$lang][$theme], $emoticonimgs[$lang][$theme], $text);
-
-        // Recover all the <script> zones to text
-        if ($excludes) {
-            $text = str_replace(array_keys($excludes), $excludes, $text);
-        }
+        return $resulthtml;
     }
 }
diff --git a/filter/emoticon/tests/filter_test.php b/filter/emoticon/tests/filter_test.php
index da3576a5419..10ee76e8303 100644
--- a/filter/emoticon/tests/filter_test.php
+++ b/filter/emoticon/tests/filter_test.php
@@ -34,29 +34,124 @@ require_once($CFG->dirroot . '/filter/emoticon/filter.php'); // Include the code
 class filter_emoticon_testcase extends advanced_testcase {
 
     /**
-     * Verify configured target formats are observed. Just that.
+     * Tests the filter doesn't affect nolink classes.
+     *
+     * @dataProvider filter_emoticon_provider
      */
-    public function test_filter_emoticon_formats() {
-
-        $this->resetAfterTest(true); // We are modifying the config.
+    public function test_filter_emoticon($input, $format, $expected) {
+        $this->resetAfterTest();
 
         $filter = new testable_filter_emoticon();
+        $this->assertEquals($expected, $filter->filter($input, [
+                'originalformat' => $format,
+            ]));
+    }
 
-        // Verify texts not matching target formats aren't filtered.
+    /**
+     * The data provider for filter emoticon tests.
+     *
+     * @return  array
+     */
+    public function filter_emoticon_provider() {
+        $grr = '(grr)';
+        return [
+            'FORMAT_MOODLE is not filtered' => [
+                'input' => $grr,
+                'format' => FORMAT_MOODLE,
+                'expected' => $grr,
+            ],
+            'FORMAT_MARKDOWN is not filtered' => [
+                'input' => $grr,
+                'format' => FORMAT_MARKDOWN,
+                'expected' => $grr,
+            ],
+            'FORMAT_PLAIN is not filtered' => [
+                'input' => $grr,
+                'format' => FORMAT_PLAIN,
+                'expected' => $grr,
+            ],
+            'FORMAT_HTML is filtered' => [
+                'input' => $grr,
+                'format' => FORMAT_HTML,
+                'expected' => $this->get_converted_content_for_emoticon($grr),
+            ],
+            'Script tag should not be processed' => [
+                'input' => "<script language='javascript'>alert('{$grr}');</script>",
+                'format' => FORMAT_HTML,
+                'expected' => "<script language='javascript'>alert('{$grr}');</script>",
+            ],
+            'Basic nolink should not be processed' => [
+                'input' => '<span class="nolink">(n)</span>',
+                'format' => FORMAT_HTML,
+                'expected' => '<span class="nolink">(n)</span>',
+            ],
+            'Nested nolink should not be processed' => [
+                'input' => '<span class="nolink"><span>(n)</span>(n)</span>',
+                'format' => FORMAT_HTML,
+                'expected' => '<span class="nolink"><span>(n)</span>(n)</span>',
+            ],
+            'Nested nolink should not be processed but following emoticon' => [
+                'input' => '<span class="nolink"><span>(n)</span>(n)</span>(n)',
+                'format' => FORMAT_HTML,
+                'expected' => '<span class="nolink"><span>(n)</span>(n)</span>' . $this->get_converted_content_for_emoticon('(n)'),
+            ],
+        ];
+    }
+
+    /**
+     * Translate the text for a single emoticon into the rendered value.
+     *
+     * @param   string  $text The text to translate.
+     * @return  string
+     */
+    public function get_converted_content_for_emoticon($text) {
+        global $OUTPUT;
+        $manager = get_emoticon_manager();
+        $emoticons = $manager->get_emoticons();
+        foreach ($emoticons as $emoticon) {
+            if ($emoticon->text == $text) {
+                return $OUTPUT->render($manager->prepare_renderable_emoticon($emoticon));
+            }
+        }
+
+        return $text;
+    }
+
+    /**
+     * Tests the filter doesn't break anything if activated but invalid format passed.
+     *
+     */
+    public function test_filter_invalidformat() {
+        global $PAGE;
+        $this->resetAfterTest();
+
+        $filter = new testable_filter_emoticon();
+        $input = '(grr)';
         $expected = '(grr)';
-        $options = array('originalformat' => FORMAT_MOODLE); // Only FORMAT_HTML is filtered, see {@link testable_filter_emoticon}.
-        $this->assertEquals($expected, $filter->filter('(grr)', $options));
 
-        $options = array('originalformat' => FORMAT_MARKDOWN); // Only FORMAT_HTML is filtered, see {@link testable_filter_emoticon}.
-        $this->assertEquals($expected, $filter->filter('(grr)', $options));
+        $this->assertEquals($expected, $filter->filter($input, [
+            'originalformat' => 'ILLEGALFORMAT',
+        ]));
+    }
 
-        $options = array('originalformat' => FORMAT_PLAIN); // Only FORMAT_HTML is filtered, see {@link testable_filter_emoticon}.
-        $this->assertEquals($expected, $filter->filter('(grr)', $options));
+    /**
+     * Tests the filter doesn't break anything if activated but no emoticons available.
+     *
+     */
+    public function test_filter_emptyemoticons() {
+        global $CFG;
+        $this->resetAfterTest();
+        // Empty the emoticons array.
+        $CFG->emoticons = null;
 
-        // And texts matching target formats are filtered.
-        $expected = '<img class="icon emoticon" alt="angry" title="angry" src="https://www.example.com/moodle/theme/image.php/_s/boost/core/1/s/angry" />';
-        $options = array('originalformat' => FORMAT_HTML); // Only FORMAT_HTML is filtered, see {@link testable_filter_emoticon}.
-        $this->assertEquals($expected, $filter->filter('(grr)', $options));
+        $filter = new filter_emoticon(context_system::instance(), array('originalformat' => FORMAT_HTML));
+
+        $input = '(grr)';
+        $expected = '(grr)';
+
+        $this->assertEquals($expected, $filter->filter($input, [
+            'originalformat' => FORMAT_HTML,
+        ]));
     }
 }
 
@@ -65,6 +160,9 @@ class filter_emoticon_testcase extends advanced_testcase {
  */
 class testable_filter_emoticon extends filter_emoticon {
     public function __construct() {
+        // Reset static emoticon caches.
+        parent::$emoticontexts = array();
+        parent::$emoticonimgs = array();
         // Use this context for filtering.
         $this->context = context_system::instance();
         // Define FORMAT_HTML as only one filtering in DB.