diff --git a/ext/dom/tests/modern/css_selectors/gh25210.phpt b/ext/dom/tests/modern/css_selectors/gh25210.phpt
new file mode 100644
index 000000000000..4db166d78c49
--- /dev/null
+++ b/ext/dom/tests/modern/css_selectors/gh25210.phpt
@@ -0,0 +1,33 @@
+--TEST--
+GH-25210 (querySelectorAll() returns duplicates for selector lists with combinators)
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$dom = Dom\HTMLDocument::createFromString(
+    '<!DOCTYPE html><ul><li>a<ol><li id="x">b</li></ol></li></ul>'
+);
+
+foreach ([$dom, $dom->querySelector('ul')] as $context) {
+    foreach (['ul li, ol li', 'ol li, ul li', 'li, li', 'ul li, ol > li', '#x, ul li'] as $selector) {
+        $ids = [];
+        foreach ($context->querySelectorAll($selector) as $node) {
+            $ids[] = $node->id ?: $node->textContent;
+        }
+        echo $selector, ': ', implode(' ', $ids), "\n";
+    }
+}
+
+?>
+--EXPECT--
+ul li, ol li: ab x
+ol li, ul li: ab x
+li, li: ab x
+ul li, ol > li: ab x
+#x, ul li: ab x
+ul li, ol li: ab x
+ol li, ul li: ab x
+li, li: ab x
+ul li, ol > li: ab x
+#x, ul li: ab x