diff --git a/.circleci/config.yml b/.circleci/config.yml
index f6429ee..15d15c1 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -51,6 +51,10 @@ jobs:
     docker:
       - image: 'cimg/php:8.0'
     steps: *php_unit_test_steps
+  php_81_tests:
+    docker:
+      - image: 'cimg/php:8.1'
+    steps: *php_unit_test_steps
 workflows:
   version: 2
   commit:
@@ -68,3 +72,6 @@ workflows:
       - php_80_tests:
           requires:
             - php_setup
+      - php_81_tests:
+          requires:
+            - php_setup
diff --git a/src/BBCode.php b/src/BBCode.php
index 219c721..4097d27 100644
--- a/src/BBCode.php
+++ b/src/BBCode.php
@@ -762,7 +762,7 @@ public function nl2br($string) {
     // and performs exactly the same function.  Unlike html_entity_decode, it
     // works on older versions of PHP (prior to 4.3.0).
     public function unHTMLEncode($string) {
-        return html_entity_decode($string);
+        return html_entity_decode($string, ENT_QUOTES);
     }
 
 
@@ -903,7 +903,7 @@ public function isValidEmail($string) {
     public function htmlEncode($string) {
         if ($this->escape_content) {
             if (!$this->allow_ampersand) {
-                return htmlspecialchars($string);
+                return htmlspecialchars($string, ENT_QUOTES);
             } else {
                 return str_replace(['<', '>', '"'], ['&lt;', '&gt;', '&quot;'], $string);
             }
@@ -995,9 +995,9 @@ protected function processSmileys($string) {
                         // For non-smiley text, we just pass it through htmlspecialchars.
                         $output .= $this->htmlEncode($token);
                     } else {
-                        $alt = htmlspecialchars($token);
+                        $alt = htmlspecialchars($token, ENT_QUOTES);
                         if ($smiley_count < $this->max_smileys || $this->max_smileys < 0) {
-                            $output .= "<img src=\"".htmlspecialchars($this->smiley_url.'/'.$this->smileys[$token]).'"'
+                            $output .= "<img src=\"".htmlspecialchars($this->smiley_url.'/'.$this->smileys[$token], ENT_QUOTES).'"'
 //								. "\" width=\"{$info[ 0 ]}\" height=\"{$info[ 1 ]}\""
                                 ." alt=\"$alt\" title=\"$alt\" class=\"bbcode_smiley\" />";
                         } else {
@@ -1310,7 +1310,7 @@ public function fillTemplate($template, $insert_array, $default_array = []) {
                     } elseif (isset($flags['k'])) {
                         $value = $this->wikify($value);
                     } elseif (isset($flags['h'])) {
-                        $value = htmlspecialchars($value);
+                        $value = htmlspecialchars($value, ENT_QUOTES);
                     } elseif (isset($flags['u'])) {
                         $value = urlencode($value);
                     }
@@ -1658,7 +1658,7 @@ protected function dumpStack($array = false, $raw = false) {
 
             switch ($item[self::BBCODE_STACK_TOKEN]) {
                 case self::BBCODE_TEXT:
-                    $string .= "\"".htmlspecialchars($item[self::BBCODE_STACK_TEXT])."\" ";
+                    $string .= "\"".htmlspecialchars($item[self::BBCODE_STACK_TEXT], ENT_QUOTES)."\" ";
                     break;
                 case self::BBCODE_WS:
                     $string .= "WS ";
@@ -1667,7 +1667,7 @@ protected function dumpStack($array = false, $raw = false) {
                     $string .= "NL ";
                     break;
                 case self::BBCODE_TAG:
-                    $string .= "[".htmlspecialchars($item[self::BBCODE_STACK_TAG]['_name'])."] ";
+                    $string .= "[".htmlspecialchars($item[self::BBCODE_STACK_TAG]['_name'], ENT_QUOTES)."] ";
                     break;
                 default:
                     $string .= "unknown ";
@@ -1853,7 +1853,7 @@ protected function doLimit() {
     //
     //   $params is an array of key => value parameters associated with the tag; for example,
     //        in [smiley src=smile alt=:-)], it's Array('src' => "smile", 'alt' => ":-)").
-    //        These keys and values have NOT beel passed through htmlspecialchars().
+    //        These keys and values have NOT been passed through htmlspecialchars().
     //
     //   $contents is the body of the tag during BBCODE_OUTPUT.  For example, in
     //        [b]Hello[/b], it's "Hello".  THIS VALUE IS ALWAYS HTML, not BBCode.
@@ -1970,7 +1970,7 @@ public function doTag($action, $tag_name, $default_value, $params, $contents) {
                             break;
                         }
                         if (isset($params[$possible_content]) && strlen($params[$possible_content]) > 0) {
-                            $result = htmlspecialchars($params[$possible_content]);
+                            $result = htmlspecialchars($params[$possible_content], ENT_QUOTES);
                             break;
                         }
                     }
@@ -2211,7 +2211,7 @@ protected function processVerbatimTag($tag_name, $tag_params, $tag_rule) {
 
             $this->stack[] = Array(
                 self::BBCODE_STACK_TOKEN => $token_type,
-                self::BBCODE_STACK_TEXT => htmlspecialchars($this->lexer->text),
+                self::BBCODE_STACK_TEXT => htmlspecialchars($this->lexer->text, ENT_QUOTES),
                 self::BBCODE_STACK_TAG => $this->lexer->tag,
                 self::BBCODE_STACK_CLASS => $this->current_class,
             );
diff --git a/src/BBCodeLibrary.php b/src/BBCodeLibrary.php
index cf068be..e206e61 100644
--- a/src/BBCodeLibrary.php
+++ b/src/BBCodeLibrary.php
@@ -450,13 +450,13 @@ public function doURL(BBCode $bbcode, $action, $name, $default, $params, $conten
             }
 
             if ($bbcode->getURLTargetable() !== false && isset($params['target'])) {
-                $target = ' target="'.htmlspecialchars($params['target']).'"';
+                $target = ' target="'.htmlspecialchars($params['target'], ENT_QUOTES).'"';
             } else {
                 $target = '';
             }
 
             if ($bbcode->getURLTarget() !== false && empty($target)) {
-                $target = ' target="'.htmlspecialchars($bbcode->getURLTarget()).'"';
+                $target = ' target="'.htmlspecialchars($bbcode->getURLTarget(), ENT_QUOTES).'"';
             }
 
             // If $detect_urls is on, it's possble the $content is already
@@ -465,7 +465,7 @@ public function doURL(BBCode $bbcode, $action, $name, $default, $params, $conten
 
             return $bbcode->fillTemplate($bbcode->getURLTemplate(), array("url" => $url, "target" => $target, "content" => $content));
         } else {
-            return htmlspecialchars($params['_tag']).$content.htmlspecialchars($params['_endtag']);
+            return htmlspecialchars($params['_tag'], ENT_QUOTES).$content.htmlspecialchars($params['_endtag'], ENT_QUOTES);
         }
     }
 
@@ -498,7 +498,7 @@ public function doEmail(BBCode $bbcode, $action, $name, $default, $params, $cont
         if ($bbcode->isValidEmail($email)) {
             return $bbcode->fillTemplate($bbcode->getEmailTemplate(), array("email" => $email, "content" => $content));
         } else {
-            return htmlspecialchars($params['_tag']).$content.htmlspecialchars($params['_endtag']);
+            return htmlspecialchars($params['_tag'], ENT_QUOTES).$content.htmlspecialchars($params['_endtag'], ENT_QUOTES);
         }
     }
 
@@ -662,16 +662,16 @@ public function doImage(BBCode $bbcode, $action, $name, $default, $params, $cont
                 $localImgURL = $bbcode->getLocalImgURL();
 
                 return "<img src=\""
-                .htmlspecialchars((empty($localImgURL) ? '' : $localImgURL.'/').ltrim($urlParts['path'], '/')).'" alt="'
-                .htmlspecialchars(basename($content)).'" class="bbcode_img" />';
+                .htmlspecialchars((empty($localImgURL) ? '' : $localImgURL.'/').ltrim($urlParts['path'], '/'), ENT_QUOTES).'" alt="'
+                .htmlspecialchars(basename($content), ENT_QUOTES).'" class="bbcode_img" />';
             } elseif ($bbcode->isValidURL($content, false)) {
                 // Remote URL, or at least we don't know where it is.
-                return '<img src="'.htmlspecialchars($content).'" alt="'
-                .htmlspecialchars(basename($content)).'" class="bbcode_img" />';
+                return '<img src="'.htmlspecialchars($content, ENT_QUOTES).'" alt="'
+                .htmlspecialchars(basename($content), ENT_QUOTES).'" class="bbcode_img" />';
             }
         }
 
-        return htmlspecialchars($params['_tag']).htmlspecialchars($content).htmlspecialchars($params['_endtag']);
+        return htmlspecialchars($params['_tag'], ENT_QUOTES).htmlspecialchars($content, ENT_QUOTES).htmlspecialchars($params['_endtag'], ENT_QUOTES);
     }
 
     /**
@@ -730,21 +730,21 @@ public function doQuote(BBCode $bbcode, $action, $name, $default, $params, $cont
         }
 
         if (isset($params['name'])) {
-            $title = htmlspecialchars(trim($params['name']))." wrote";
+            $title = htmlspecialchars(trim($params['name']), ENT_QUOTES)." wrote";
             if (isset($params['date'])) {
-                $title .= " on ".htmlspecialchars(trim($params['date']));
+                $title .= " on ".htmlspecialchars(trim($params['date']), ENT_QUOTES);
             }
             $title .= ":";
             if (isset($params['url'])) {
                 $url = trim($params['url']);
                 if ($bbcode->isValidURL($url)) {
-                    $title = "<a href=\"".htmlspecialchars($params['url'])."\">".$title."</a>";
+                    $title = "<a href=\"".htmlspecialchars($params['url'], ENT_QUOTES)."\">".$title."</a>";
                 }
             }
         } elseif (!is_string($default)) {
             $title = "Quote:";
         } else {
-            $title = htmlspecialchars(trim($default))." wrote:";
+            $title = htmlspecialchars(trim($default), ENT_QUOTES)." wrote:";
         }
 
         return $bbcode->fillTemplate($bbcode->getQuoteTemplate(), array("title" => $title, "content" => $content));
diff --git a/tests/ConformanceTest.php b/tests/ConformanceTest.php
index 0f8d891..8a46569 100644
--- a/tests/ConformanceTest.php
+++ b/tests/ConformanceTest.php
@@ -52,14 +52,14 @@ public function provideInputValidationTests() {
                 'html' => "This is [/ a tag.",
             ]],
             [[
-                'descr' => "Broken [ tags before [b]real tags[/b] don't break the real tags.",
-                'bbcode' => "Broken [ tags before [b]real tags[/b] don't break the real tags.",
-                'html' => "Broken [ tags before <b>real tags</b> don't break the real tags.",
+                'descr' => "Broken [ tags before [b]real tags[/b] do not break the real tags.",
+                'bbcode' => "Broken [ tags before [b]real tags[/b] do not break the real tags.",
+                'html' => "Broken [ tags before <b>real tags</b> do not break the real tags.",
             ]],
             [[
-                'descr' => "Broken [tags before [b]real tags[/b] don't break the real tags.",
-                'bbcode' => "Broken [tags before [b]real tags[/b] don't break the real tags.",
-                'html' => "Broken [tags before <b>real tags</b> don't break the real tags.",
+                'descr' => "Broken [tags before [b]real tags[/b] do not break the real tags.",
+                'bbcode' => "Broken [tags before [b]real tags[/b] do not break the real tags.",
+                'html' => "Broken [tags before <b>real tags</b> do not break the real tags.",
             ]],
             [[
                 'descr' => "[i][b]Mis-ordered nesting[/i][/b] gets fixed.",
@@ -119,9 +119,25 @@ public function provideInputValidationTests() {
     public function provideSpecialCharacterTests() {
         $result = [
             [[
-                'descr' => "& and < and > and \" get replaced with HTML-safe equivalents.",
+                'descr' => "& and < and > and \" and ' get replaced with HTML-safe equivalents.",
                 'bbcode' => "This <woo!> &\"yeah!\" 'sizzle'",
-                'html' => "This &lt;woo!&gt; &amp;&quot;yeah!&quot; 'sizzle'",
+                'html' => "This &lt;woo!&gt; &amp;&quot;yeah!&quot; &#039;sizzle&#039;",
+            ]],
+            [[
+                'descr' => "& and < and > and \" and ' do NOT get replaced with HTML-safe equivalents if setEscapeContent(false).",
+                'bbcode' => "This <woo!> &\"yeah!\" 'sizzle'",
+                'html' => "This <woo!> &\"yeah!\" 'sizzle'",
+                'escape_content' => false,
+            ]],
+            [[
+                'descr' => "Single quotes in tags are NOT considered special characters.",
+                'bbcode' => "[wiki='foo' title='bar']",
+                'html' => "<a href=\"/?page=foo\" class=\"bbcode_wiki\">bar</a>",
+            ]],
+            [[
+                'descr' => "Double quotes in tags are NOT considered special characters.",
+                'bbcode' => "[wiki=\"foo\" title=\"bar\"]",
+                'html' => "<a href=\"/?page=foo\" class=\"bbcode_wiki\">bar</a>",
             ]],
             [[
                 'descr' => ":-) produces a smiley <img> element.",
@@ -189,7 +205,7 @@ public function provideSpecialCharacterTests() {
             [[
                 'descr' => "['] comments may *not* contain newlines.",
                 'bbcode' => "This is a test of the [' emergency\n\rbroadcasting] system.",
-                'html' => "This is a test of the [' emergency<br>\nbroadcasting] system.",
+                'html' => "This is a test of the [&#039; emergency<br>\nbroadcasting] system.",
             ]],
             [[
                 'descr' => "[!-- --] produces a comment.",
@@ -378,10 +394,15 @@ public function provideInlineConversionTests() {
                 'html' => "This is a test of the <span style=\"font-family:'Times New Roman'\">emergency broadcasting system</span>.",
             ]],
             [[
-                'descr' => "[font=\"Courier New\"] gets correctly converted (quoted default value).",
+                'descr' => "[font=\"Courier New\"] gets correctly converted (double quoted default value).",
                 'bbcode' => "This is a test of the [font=\"Courier New\"]emergency broadcasting system[/font].",
                 'html' => "This is a test of the <span style=\"font-family:'Courier New'\">emergency broadcasting system</span>.",
             ]],
+            [[
+                'descr' => "[font='Courier New'] gets correctly converted (single quoted default value).",
+                'bbcode' => "This is a test of the [font='Courier New']emergency broadcasting system[/font].",
+                'html' => "This is a test of the <span style=\"font-family:'Courier New'\">emergency broadcasting system</span>.",
+            ]],
             [[
                 'descr' => "[font=\"Courier New\" blarg size=1] gets converted (floating parameter ignored).",
                 'bbcode' => "This is a test of the [font=\"Courier New\" blarg size=1]emergency broadcasting system[/font].",
@@ -425,7 +446,7 @@ public function provideInlineConversionTests() {
             [[
                 'descr' => "[spoiler] gets converted.",
                 'bbcode' => "Ssh, don't tell, but [spoiler]Darth is Luke's father[/spoiler]!",
-                'html' => "Ssh, don't tell, but <span class=\"bbcode_spoiler\">Darth is Luke's father</span>!",
+                'html' => "Ssh, don&#039;t tell, but <span class=\"bbcode_spoiler\">Darth is Luke&#039;s father</span>!",
             ]],
             [[
                 'descr' => "[acronym] gets converted.",
@@ -721,7 +742,7 @@ public function provideUrlLikeTagTests() {
             [[
                 'descr' => "The [[wiki]] special tag does not convert [a-zA-Z0-9'\".:_-].",
                 'bbcode' => "This is a test of the [[\"Ab1cd'Ef2gh_Ij3kl.,Mn4op:Qr9st-Uv0wx\"]] tag.",
-                'html' => "This is a test of the <a href=\"/?page=%22Ab1cd%27Ef2gh_Ij3kl.%2CMn4op%3AQr9st_Uv0wx%22\" class=\"bbcode_wiki\">&quot;Ab1cd'Ef2gh_Ij3kl.,Mn4op:Qr9st-Uv0wx&quot;</a> tag.",
+                'html' => "This is a test of the <a href=\"/?page=%22Ab1cd%27Ef2gh_Ij3kl.%2CMn4op%3AQr9st_Uv0wx%22\" class=\"bbcode_wiki\">&quot;Ab1cd&#039;Ef2gh_Ij3kl.,Mn4op:Qr9st-Uv0wx&quot;</a> tag.",
             ]],
             [[
                 'descr' => "The [[wiki]] special tag can contain spaces.",
@@ -761,23 +782,23 @@ public function provideImageTests() {
         $result = [
             [[
                 'descr' => "[img] produces an image.",
-                'bbcode' => "This is Google's logo: [img]http://www.google.com/intl/en_ALL/images/logo.gif[/img].",
-                'html' => "This is Google's logo: <img src=\"http://www.google.com/intl/en_ALL/images/logo.gif\" alt=\"logo.gif\" class=\"bbcode_img\" />.",
+                'bbcode' => "This is the Google logo: [img]http://www.google.com/intl/en_ALL/images/logo.gif[/img].",
+                'html' => "This is the Google logo: <img src=\"http://www.google.com/intl/en_ALL/images/logo.gif\" alt=\"logo.gif\" class=\"bbcode_img\" />.",
             ]],
             [[
                 'descr' => "[img] disallows a javascript: URL.",
-                'bbcode' => "This is Google's logo: [img]javascript:alert()[/img].",
-                'html' => "This is Google's logo: [img]javascript:alert()[/img].",
+                'bbcode' => "This is the Google logo: [img]javascript:alert()[/img].",
+                'html' => "This is the Google logo: [img]javascript:alert()[/img].",
             ]],
             [[
                 'descr' => "[img] disallows a URL with an unknown protocol type.",
-                'bbcode' => "This is Google's logo: [img]foobar:bar.jpg[/img].",
-                'html' => "This is Google's logo: [img]foobar:bar.jpg[/img].",
+                'bbcode' => "This is the Google logo: [img]foobar:bar.jpg[/img].",
+                'html' => "This is the Google logo: [img]foobar:bar.jpg[/img].",
             ]],
             [[
                 'descr' => "[img] disallows HTML content.",
-                'bbcode' => "This is Google's logo: [img]<a href='javascript:alert(\"foo\")'>click me</a>[/img].",
-                'html' => "This is Google's logo: [img]&lt;a href='javascript:alert(&quot;foo&quot;)'&gt;click me&lt;/a&gt;[/img].",
+                'bbcode' => "This is the Google logo: [img]<a href='javascript:alert(\"foo\")'>click me</a>[/img].",
+                'html' => "This is the Google logo: [img]&lt;a href=&#039;javascript:alert(&quot;foo&quot;)&#039;&gt;click me&lt;/a&gt;[/img].",
             ]],
             [[
                 'descr' => "[img] can produce a local image.",
@@ -865,7 +886,7 @@ public function provideBlockTagConversionTests() {
                     . "\n<div class=\"bbcode_code\">\n"
                     . "<div class=\"bbcode_code_head\">Code:</div>\n"
                     . "<div class=\"bbcode_code_body\" style=\"white-space:pre\">A [b]and[/b] &amp; &lt;woo&gt;!\n"
-                    . "\tAnd a ['hey'] and a [/nonny] and a ho ho ho!</div>\n"
+                    . "\tAnd a [&#039;hey&#039;] and a [/nonny] and a ho ho ho!</div>\n"
                     . "</div>\n"
                     . "Also not code.",
             ]],
@@ -880,7 +901,7 @@ public function provideBlockTagConversionTests() {
                 'html' => "Not code."
                     . "\n<div class=\"bbcode_code\">\n"
                     . "<div class=\"bbcode_code_head\">Code:</div>\n"
-                    . "<div class=\"bbcode_code_body\" style=\"white-space:pre\">\$foo['bar'] = 42;\n"
+                    . "<div class=\"bbcode_code_body\" style=\"white-space:pre\">\$foo[&#039;bar&#039;] = 42;\n"
                     . "if (\$foo[&quot;bar&quot;] &lt; 42) \$foo[] = 0;</div>\n"
                     . "</div>\n"
                     . "Also not code.<br>\n",
@@ -1039,8 +1060,8 @@ public function provideBlockTagConversionTests() {
             ]],
             [[
                 'descr' => "[nextcol] doesn't do anything outside a [columns] block.",
-                'bbcode' => "Here's some text.[nextcol]\nHere's some more.\n",
-                'html' => "Here's some text.[nextcol]<br>\nHere's some more.<br>\n",
+                'bbcode' => "Here is some text.[nextcol]\nHere is some more.\n",
+                'html' => "Here is some text.[nextcol]<br>\nHere is some more.<br>\n",
             ]],
             [[
                 'descr' => "Bad column misuse doesn't break layouts.",
@@ -1175,6 +1196,7 @@ protected function performTest($test) {
         $bbcode->setURLTargetable($test['urltarget'] == true);
         $bbcode->setURLTarget($test['urlforcetarget']);
         $bbcode->setPlainMode($test['plainmode']);
+        $bbcode->setEscapeContent($test['escape_content'] ?? true);
 
         if ($test['tag_marker'] === '<') {
             $bbcode->setTagMarker('<');