diff --git a/ext/dom/html5_parser.c b/ext/dom/html5_parser.c
index f1dc2db53b25b..d5fe3d5c2773d 100644
--- a/ext/dom/html5_parser.c
+++ b/ext/dom/html5_parser.c
@@ -268,7 +268,10 @@ static lexbor_libxml2_bridge_status lexbor_libxml2_bridge_convert(
 
                 /* xmlIsID does some other stuff too that is irrelevant here. */
                 if (local_name_length == 2 && local_name[0] == 'i' && local_name[1] == 'd' && attr->node.ns == LXB_NS_HTML) {
-                    xmlAddID(NULL, lxml_doc, value, lxml_attr);
+                    if (xmlAddID(NULL, lxml_doc, value, lxml_attr) == 0) {
+                        /* If the ID already exists, the ID attribute still needs to be marked as an ID. */
+                        lxml_attr->atype = XML_ATTRIBUTE_ID;
+                    }
                 }
 
                 /* libxml2 doesn't support line numbers on this anyway, it derives them instead, so don't bother */
diff --git a/ext/dom/tests/modern/html/interactions/gh20281.phpt b/ext/dom/tests/modern/html/interactions/gh20281.phpt
new file mode 100644
index 0000000000000..324c5a2756331
--- /dev/null
+++ b/ext/dom/tests/modern/html/interactions/gh20281.phpt
@@ -0,0 +1,15 @@
+--TEST--
+GH-20281 (\Dom\Document::getElementById() is inconsistent after nodes are removed)
+--EXTENSIONS--
+dom
+--CREDITS--
+cscott
+--FILE--
+<?php
+$d = \Dom\HTMLDocument::createFromString('<p id="a">b</p><p id="a">c</p>', LIBXML_NOERROR);
+$p = $d->getElementById('a');
+$p->remove();
+echo $d->getElementById('a')->textContent, "\n";
+?>
+--EXPECT--
+c
diff --git a/ext/phar/tests/tar/bug70417.phpt b/ext/phar/tests/tar/bug70417.phpt
index 4d98a18954cc3..504d7e1e387b6 100644
--- a/ext/phar/tests/tar/bug70417.phpt
+++ b/ext/phar/tests/tar/bug70417.phpt
@@ -3,32 +3,17 @@ Bug #70417 (PharData::compress() doesn't close temp file)
 --EXTENSIONS--
 phar
 zlib
---SKIPIF--
-<?php
-
-exec('lsof -p ' . getmypid(), $out, $status);
-if ($status !== 0) {
-    die("skip lsof(8) not available");
-}
-if (!str_starts_with($out[0], 'COMMAND')) {
-    die("skip Might be a different lsof");
-}
-?>
 --FILE--
 <?php
-function countOpenFiles() {
-    exec('lsof -p ' . escapeshellarg(getmypid()) . ' 2> /dev/null', $out);  // Note: valgrind can produce false positives for /usr/bin/lsof
-    return count($out);
-}
 $filename = __DIR__ . '/bug70417.tar';
 @unlink("$filename.gz");
-$openFiles1 = countOpenFiles();
+$resBefore = count(get_resources());
 $arch = new PharData($filename);
 $arch->addFromString('foo', 'bar');
 $arch->compress(Phar::GZ);
 unset($arch);
-$openFiles2 = countOpenFiles();
-var_dump($openFiles1 === $openFiles2);
+$resAfter = count(get_resources());
+var_dump($resBefore === $resAfter);
 ?>
 --CLEAN--
 <?php