diff --git a/packages/guides-restructured-text/src/RestructuredText/Parser/InlineLexer.php b/packages/guides-restructured-text/src/RestructuredText/Parser/InlineLexer.php
index 25a6a96bd..267ea06c9 100644
--- a/packages/guides-restructured-text/src/RestructuredText/Parser/InlineLexer.php
+++ b/packages/guides-restructured-text/src/RestructuredText/Parser/InlineLexer.php
@@ -130,7 +130,7 @@ protected function getType(string &$value)
             return self::ANONYMOUSE_REFERENCE;
         }
 
-        if (preg_match('/[a-z0-9-]+_{1}/i', $value)) {
+        if (preg_match('/[a-z0-9-]+_{1}(?=\s|$)/i', $value)) {
             return self::NAMED_REFERENCE;
         }
 
diff --git a/packages/guides-restructured-text/tests/unit/Parser/InlineLexerTest.php b/packages/guides-restructured-text/tests/unit/Parser/InlineLexerTest.php
new file mode 100644
index 000000000..aac6368e6
--- /dev/null
+++ b/packages/guides-restructured-text/tests/unit/Parser/InlineLexerTest.php
@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace phpDocumentor\Guides\RestructuredText\Parser;
+
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+use function PHPUnit\Framework\assertEquals;
+
+class InlineLexerTest extends TestCase
+{
+    /** @param int[] $result */
+    #[DataProvider('inlineLexerProvider')]
+    public function testLexer(string $input, array $result): void
+    {
+        $lexer = new InlineLexer();
+        $lexer->setInput($input);
+        $lexer->moveNext();
+        $lexer->moveNext();
+        foreach ($result as $tokenType) {
+            assertEquals($tokenType, $lexer->token?->type);
+        }
+    }
+
+    /** @return array<string, array<string | int[]>> */
+    public static function inlineLexerProvider(): array
+    {
+        return [
+            'Backtick' => [
+                '`',
+                [InlineLexer::BACKTICK],
+            ],
+            'Normal Url' => [
+                'http://www.test.com',
+                [InlineLexer::HYPERLINK],
+            ],
+            'HTTPS Url' => [
+                'https://www.test.com',
+                [InlineLexer::HYPERLINK],
+            ],
+            'String with underscore' => [
+                'EXT:css_styled_content/static/v6.2',
+                [InlineLexer::WORD],
+            ],
+            'Named Reference' => [
+                'css_',
+                [InlineLexer::NAMED_REFERENCE],
+            ],
+            'Named Reference in sentence' => [
+                'css_ and something',
+                [InlineLexer::NAMED_REFERENCE],
+            ],
+        ];
+    }
+}