diff --git a/ext/dom/dom_iterators.c b/ext/dom/dom_iterators.c
index a6e6493ccb7..ef81ecaaf73 100644
--- a/ext/dom/dom_iterators.c
+++ b/ext/dom/dom_iterators.c
@@ -188,8 +188,19 @@ static void php_dom_iterator_move_forward(zend_object_iterator *iter) /* {{{ */
 			} else {
 				if (objmap->nodetype == XML_ATTRIBUTE_NODE ||
 					objmap->nodetype == XML_ELEMENT_NODE) {
-					curnode = (xmlNodePtr)((php_libxml_node_ptr *)intern->ptr)->node;
-					curnode = curnode->next;
+
+					/* Note: keep legacy behaviour for non-spec mode. */
+					if (php_dom_follow_spec_intern(intern) && php_dom_is_cache_tag_stale_from_doc_ptr(&iterator->cache_tag, intern->document)) {
+						php_dom_mark_cache_tag_up_to_date_from_doc_ref(&iterator->cache_tag, intern->document);
+						curnode = dom_fetch_first_iteration_item(objmap);
+						zend_ulong index = 0;
+						while (curnode != NULL && index++ < iter->index) {
+							curnode = curnode->next;
+						}
+					} else {
+						curnode = (xmlNodePtr)((php_libxml_node_ptr *)intern->ptr)->node;
+						curnode = curnode->next;
+					}
 				} else {
 					/* The collection is live, we nav the tree from the base object if we cannot
 					 * use the cache to restart from the last point. */
diff --git a/ext/dom/php_dom.h b/ext/dom/php_dom.h
index e64695f07b1..26035832d95 100644
--- a/ext/dom/php_dom.h
+++ b/ext/dom/php_dom.h
@@ -262,6 +262,13 @@ static zend_always_inline void php_dom_mark_cache_tag_up_to_date_from_node(php_l
 	}
 }
 
+static zend_always_inline void php_dom_mark_cache_tag_up_to_date_from_doc_ref(php_libxml_cache_tag *cache_tag, php_libxml_ref_obj *document)
+{
+	ZEND_ASSERT(cache_tag != NULL);
+	ZEND_ASSERT(document != NULL);
+	cache_tag->modification_nr = document->cache_tag.modification_nr;
+}
+
 static zend_always_inline bool php_dom_follow_spec_node(const xmlNode *node)
 {
 	ZEND_ASSERT(node != NULL);
diff --git a/ext/dom/tests/gh13863.phpt b/ext/dom/tests/gh13863.phpt
new file mode 100644
index 00000000000..e9a7058c341
--- /dev/null
+++ b/ext/dom/tests/gh13863.phpt
@@ -0,0 +1,164 @@
+--TEST--
+GH-13863 (Removal during NodeList iteration breaks loop)
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+enum DomType {
+    case Legacy;
+    case Modern;
+}
+
+function createTestDoc(DomType $type) {
+    $xml = <<<EOXML
+    <x>
+        <item1 />
+        <item2 />
+        <item3 />
+        <item4 />
+        <item5 />
+    </x>
+    EOXML;
+
+    if ($type === DomType::Legacy) {
+        $doc = new DOMDocument();
+        $doc->preserveWhiteSpace = false;
+        $doc->loadXML($xml);
+    } else {
+        $doc = DOM\XMLDocument::createFromString($xml, LIBXML_NOBLANKS);
+    }
+
+    return $doc;
+}
+
+foreach ([DomType::Legacy, DomType::Modern] as $case) {
+    $name = match ($case) {
+        DomType::Legacy => 'Legacy',
+        DomType::Modern => 'Modern',
+    };
+
+    echo "--- $name test remove index 2 at index 2 ---\n";
+
+    $doc = createTestDoc($case);
+
+    foreach ($doc->documentElement->childNodes as $i => $node) {
+        var_dump($doc->documentElement->childNodes->item($i) === $node);
+        var_dump($i, $node->localName);
+        if ($i === 2) {
+            $node->remove();
+        }
+    }
+
+    echo $doc->saveXML(), "\n";
+
+    echo "--- $name test remove index 1 at index 2 ---\n";
+
+    $doc = createTestDoc($case);
+
+    foreach ($doc->documentElement->childNodes as $i => $node) {
+        var_dump($doc->documentElement->childNodes->item($i) === $node);
+        var_dump($i, $node->localName);
+        if ($i === 2) {
+            $doc->documentElement->childNodes[1]->remove();
+        }
+    }
+
+    echo $doc->saveXML(), "\n";
+
+    echo "--- $name test remove all ---\n";
+
+    $doc = createTestDoc($case);
+
+    foreach ($doc->documentElement->childNodes as $i => $node) {
+        var_dump($doc->documentElement->childNodes->item($i) === $node);
+        var_dump($i, $node->localName);
+        $node->remove();
+    }
+
+    echo $doc->saveXML(), "\n";
+}
+
+?>
+--EXPECT--
+--- Legacy test remove index 2 at index 2 ---
+bool(true)
+int(0)
+string(5) "item1"
+bool(true)
+int(1)
+string(5) "item2"
+bool(true)
+int(2)
+string(5) "item3"
+<?xml version="1.0"?>
+<x><item1/><item2/><item4/><item5/></x>
+
+--- Legacy test remove index 1 at index 2 ---
+bool(true)
+int(0)
+string(5) "item1"
+bool(true)
+int(1)
+string(5) "item2"
+bool(true)
+int(2)
+string(5) "item3"
+bool(false)
+int(3)
+string(5) "item4"
+bool(false)
+int(4)
+string(5) "item5"
+<?xml version="1.0"?>
+<x><item1/><item3/><item4/><item5/></x>
+
+--- Legacy test remove all ---
+bool(true)
+int(0)
+string(5) "item1"
+<?xml version="1.0"?>
+<x><item2/><item3/><item4/><item5/></x>
+
+--- Modern test remove index 2 at index 2 ---
+bool(true)
+int(0)
+string(5) "item1"
+bool(true)
+int(1)
+string(5) "item2"
+bool(true)
+int(2)
+string(5) "item3"
+bool(true)
+int(3)
+string(5) "item5"
+<?xml version="1.0" encoding="UTF-8"?>
+<x><item1/><item2/><item4/><item5/></x>
+--- Modern test remove index 1 at index 2 ---
+bool(true)
+int(0)
+string(5) "item1"
+bool(true)
+int(1)
+string(5) "item2"
+bool(true)
+int(2)
+string(5) "item3"
+bool(true)
+int(3)
+string(5) "item5"
+<?xml version="1.0" encoding="UTF-8"?>
+<x><item1/><item3/><item4/><item5/></x>
+--- Modern test remove all ---
+bool(true)
+int(0)
+string(5) "item1"
+bool(true)
+int(1)
+string(5) "item3"
+bool(true)
+int(2)
+string(5) "item5"
+<?xml version="1.0" encoding="UTF-8"?>
+<x><item2/><item4/></x>