diff --git a/src/qtism/data/storage/xml/Utils.php b/src/qtism/data/storage/xml/Utils.php
index 8930aa811..87bbfca84 100644
--- a/src/qtism/data/storage/xml/Utils.php
+++ b/src/qtism/data/storage/xml/Utils.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /**
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -353,11 +355,71 @@ public static function valueAsString($value, $encode = true): string
             return $value === true ? 'true' : 'false';
         }
         if ($encode) {
-            return htmlspecialchars((string)$value, ENT_XML1, 'UTF-8');
+            return self::xmlSpecialChars((string)$value);
         }
         return (string)$value;
     }
 
+    private static function isInCharacterRange(int $char): bool
+    {
+        return $char == 0x09
+            || $char == 0x0A
+            || $char == 0x0D
+            || $char >= 0x20 && $char <= 0xDF77
+            || $char >= 0xE000 && $char <= 0xFFFD
+            || $char >= 0x10000 && $char <= 0x10FFFF;
+    }
+
+    public static function xmlSpecialChars(string $value): string
+    {
+        $result = '';
+
+        $last = 0;
+        $length = strlen($value);
+        $i = 0;
+
+        while ($i < $length) {
+            $r = mb_substr(substr($value, $i), 0, 1);
+            $width = strlen($r);
+            $i += $width;
+            switch ($r) {
+                case '"':
+                    $esc = '&#34;';
+                    break;
+                case "'":
+                    $esc = '&#39;';
+                    break;
+                case '&':
+                    $esc = '&amp;';
+                    break;
+                case '<':
+                    $esc = '&lt;';
+                    break;
+                case '>':
+                    $esc = '&gt;';
+                    break;
+                case "\t":
+                    $esc = '&#x9;';
+                    break;
+                case "\n":
+                    $esc = '&#xA;';
+                    break;
+                case "\r":
+                    $esc = '&#xD;';
+                    break;
+                default:
+                    if (!self::isInCharacterRange(mb_ord($r)) || (mb_ord($r) === 0xFFFD && $width === 1)) {
+                        $esc = "\u{FFFD}";
+                        break;
+                    }
+                    continue 2;
+            }
+            $result .= substr($value, $last, $i - $last - $width) . $esc;
+            $last = $i;
+        }
+        return $result . substr($value, $last);
+    }
+
     /**
      * Get the child elements of a given element by tag name. This method does
      * not behave like DOMElement::getElementsByTagName. It only returns the direct
diff --git a/test/qtismtest/data/storage/xml/XmlUtilsTest.php b/test/qtismtest/data/storage/xml/XmlUtilsTest.php
index 3e81f84cf..e0d891698 100644
--- a/test/qtismtest/data/storage/xml/XmlUtilsTest.php
+++ b/test/qtismtest/data/storage/xml/XmlUtilsTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace qtismtest\data\storage\xml;
 
 use DOMDocument;
@@ -386,11 +388,54 @@ public function testFindCustomNamespaces(): void
 ');
 
         self::assertSame(
-            ['qh5'=>'http://www.imsglobal.org/xsd/imsqtiv2p2_html5_v1p0'],
+            ['qh5' => 'http://www.imsglobal.org/xsd/imsqtiv2p2_html5_v1p0'],
             Utils::findExternalNamespaces($xml)
         );
     }
 
+    public function testValueAsStringReplaceSpecialSymbols(): void
+    {
+        $this->assertEquals("160\u{FFFD}", Utils::valueAsString("160\u{0008}"));
+    }
+
+    public function testProcessSpecialCharsetWithoutError(): void
+    {
+        $xml = ('<assessmentResult
+	xmlns="http://www.imsglobal.org/xsd/imsqti_result_v2p1"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+	<context/>
+	<testResult identifier="44127db28512-suomynona#903756e974e7#e94025be336b1f89159af64b1f6eda5d470ac8d61#local-dev-acc.nextgen-stack-local" datestamp="2024-10-30T12:56:32+00:00"/>
+	<itemResult identifier="item-1" datestamp="2024-10-30T12:56:32+00:00" sessionStatus="final">
+		<responseVariable identifier="numAttempts" cardinality="single" baseType="integer">
+			<candidateResponse>
+				<value>1</value>
+			</candidateResponse>
+		</responseVariable>
+		<responseVariable identifier="duration" cardinality="single" baseType="duration">
+			<candidateResponse>
+				<value>PT22S</value>
+			</candidateResponse>
+		</responseVariable>
+		<outcomeVariable identifier="completionStatus" cardinality="single" baseType="identifier">
+			<value>completed</value>
+		</outcomeVariable>
+		<outcomeVariable identifier="SCORE" cardinality="single" baseType="float">
+			<value>0</value>
+		</outcomeVariable>
+		<outcomeVariable identifier="MAXSCORE" cardinality="single" baseType="float">
+			<value>1</value>
+		</outcomeVariable>
+		<responseVariable identifier="RESPONSE" cardinality="single" baseType="string">
+			<candidateResponse>
+				<value>%s</value>
+			</candidateResponse>
+		</responseVariable>
+	</itemResult>
+</assessmentResult>
+');
+        $this->assertNotNull(Utils::findExternalNamespaces(sprintf($xml, Utils::valueAsString("160\u{0008}"))));
+    }
+
     public function testremoveAllButFirstOccurrence(): void
     {
         $subject = 'abc 12 abc 345abc678abc';