diff --git a/src/PhpSpreadsheet/Shared/StringHelper.php b/src/PhpSpreadsheet/Shared/StringHelper.php
index a354bf8e3..51ec36339 100644
--- a/src/PhpSpreadsheet/Shared/StringHelper.php
+++ b/src/PhpSpreadsheet/Shared/StringHelper.php
@@ -426,7 +426,7 @@ class StringHelper
      */
     public static function convertEncoding(string $textValue, string $to, string $from): string
     {
-        if (self::getIsIconvEnabled()) {
+        if (static::getIsIconvEnabled()) {
             $result = iconv($from, $to . self::$iconvOptions, $textValue);
             if (false !== $result) {
                 return $result;
diff --git a/tests/PhpSpreadsheetTests/Shared/StringHelperNoIconv.php b/tests/PhpSpreadsheetTests/Shared/StringHelperNoIconv.php
new file mode 100644
index 000000000..9f0644aca
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Shared/StringHelperNoIconv.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests\Shared;
+
+use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
+
+class StringHelperNoIconv extends StringHelper
+{
+    /**
+     * Simulate that iconv is not available.
+     */
+    public static function getIsIconvEnabled(): bool
+    {
+        return false;
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Shared/StringHelperTest.php b/tests/PhpSpreadsheetTests/Shared/StringHelperTest.php
index d7f2f38e0..1afdff562 100644
--- a/tests/PhpSpreadsheetTests/Shared/StringHelperTest.php
+++ b/tests/PhpSpreadsheetTests/Shared/StringHelperTest.php
@@ -131,4 +131,14 @@ class StringHelperTest extends TestCase
         $this->expectExceptionMessage('Unable to convert to string');
         StringHelper::convertToString($dt);
     }
+
+    public function testNoIconv(): void
+    {
+        $string = "\xBF"; // inverted question mark in ISO-8859-1
+        $expected = '¿';
+        $from = 'ISO-8859-1';
+        $to = 'UTF-8';
+        self::assertSame($expected, StringHelper::convertEncoding($string, $to, $from));
+        self::assertSame($expected, StringHelperNoIconv::convertEncoding($string, $to, $from));
+    }
 }