diff --git a/ext/dom/element.c b/ext/dom/element.c
index 4835c7fad91ad..b36c5b78dc8db 100644
--- a/ext/dom/element.c
+++ b/ext/dom/element.c
@@ -20,6 +20,7 @@
 #endif
 
 #include "php.h"
+
 #if defined(HAVE_LIBXML) && defined(HAVE_DOM)
 #include "php_dom.h"
 
@@ -74,14 +75,14 @@ PHP_METHOD(DOMElement, __construct)
 			RETURN_THROWS();
 		}
 	} else {
-	    /* If you don't pass a namespace uri, then you can't set a prefix */
-	    localname = (char *) xmlSplitQName2((xmlChar *) name, (xmlChar **) &prefix);
-	    if (prefix != NULL) {
+		/* If you don't pass a namespace uri, then you can't set a prefix */
+		localname = (char *) xmlSplitQName2((xmlChar *) name, (xmlChar **) &prefix);
+		if (prefix != NULL) {
 			xmlFree(localname);
 			xmlFree(prefix);
-	        php_dom_throw_error(NAMESPACE_ERR, 1);
-	        RETURN_THROWS();
-	    }
+			php_dom_throw_error(NAMESPACE_ERR, 1);
+			RETURN_THROWS();
+		}
 		nodep = xmlNewNode(NULL, (xmlChar *) name);
 	}
 
@@ -152,8 +153,8 @@ int dom_element_schema_type_info_read(dom_object *obj, zval *retval)
 
 static xmlNodePtr dom_get_dom1_attribute(xmlNodePtr elem, xmlChar *name) /* {{{ */
 {
-    int len;
-    const xmlChar *nqname;
+	int len;
+	const xmlChar *nqname;
 
 	nqname = xmlSplitQName3(name, &len);
 	if (nqname != NULL) {
@@ -570,9 +571,9 @@ PHP_METHOD(DOMElement, getAttributeNS)
 
 static xmlNsPtr _dom_new_reconNs(xmlDocPtr doc, xmlNodePtr tree, xmlNsPtr ns) /* {{{ */
 {
-    xmlNsPtr def;
-    xmlChar prefix[50];
-    int counter = 1;
+	xmlNsPtr def;
+	xmlChar prefix[50];
+	int counter = 1;
 
 	if ((tree == NULL) || (ns == NULL) || (ns->type != XML_NAMESPACE_DECL)) {
 		return NULL;
@@ -883,12 +884,12 @@ PHP_METHOD(DOMElement, setAttributeNodeNS)
 		RETURN_FALSE;
 	}
 
-    nsp = attrp->ns;
-    if (nsp != NULL) {
-        existattrp = xmlHasNsProp(nodep, nsp->href, attrp->name);
-    } else {
-        existattrp = xmlHasProp(nodep, attrp->name);
-    }
+	nsp = attrp->ns;
+	if (nsp != NULL) {
+		existattrp = xmlHasNsProp(nodep, nsp->href, attrp->name);
+	} else {
+		existattrp = xmlHasProp(nodep, attrp->name);
+	}
 
 	if (existattrp != NULL && existattrp->type != XML_ATTRIBUTE_DECL) {
 		if ((oldobj = php_dom_object_get_data((xmlNodePtr) existattrp)) != NULL &&
@@ -1252,7 +1253,9 @@ PHP_METHOD(DOMElement, replaceWith)
 	DOM_GET_OBJ(context, id, xmlNodePtr, intern);
 
 	dom_parent_node_after(intern, args, argc);
-	dom_child_node_remove(intern);
+	if (!dom_node_is_argument(intern, args, argc)) {
+		dom_child_node_remove(intern);
+	}
 }
 /* }}} end DOMElement::prepend */
 
diff --git a/ext/dom/parentnode.c b/ext/dom/parentnode.c
index 375c692dcad85..5c22d6636be48 100644
--- a/ext/dom/parentnode.c
+++ b/ext/dom/parentnode.c
@@ -21,6 +21,7 @@
 #endif
 
 #include "php.h"
+
 #if defined(HAVE_LIBXML) && defined(HAVE_DOM)
 #include "php_dom.h"
 
@@ -181,6 +182,10 @@ xmlNode* dom_zvals_to_fragment(php_libxml_ref_obj *document, xmlNode *contextNod
 					return NULL;
 				}
 
+				if (nodesc > 1) {
+					newNode = xmlCopyNode(newNode, 1);
+				}
+
 				if (!xmlAddChild(fragment, newNode)) {
 					xmlFree(fragment);
 
@@ -302,7 +307,9 @@ void dom_parent_node_after(dom_object *context, zval *nodes, int nodesc)
 {
 	xmlNode *prevsib = dom_object_get_node(context);
 	xmlNodePtr newchild, parentNode;
-	xmlNode *fragment;
+	xmlNode *fragment, *nextsib;
+	xmlDoc *doc;
+	bool afterlastchild;
 
 	int stricterror = dom_get_strict_error(context->document);
 
@@ -311,7 +318,10 @@ void dom_parent_node_after(dom_object *context, zval *nodes, int nodesc)
 		return;
 	}
 
+	doc = prevsib->doc;
 	parentNode = prevsib->parent;
+	nextsib = prevsib->next;
+	afterlastchild = (nextsib == NULL);
 	fragment = dom_zvals_to_fragment(context->document, parentNode, nodes, nodesc);
 
 	if (fragment == NULL) {
@@ -321,13 +331,31 @@ void dom_parent_node_after(dom_object *context, zval *nodes, int nodesc)
 	newchild = fragment->children;
 
 	if (newchild) {
-		fragment->last->next = prevsib->next;
-		prevsib->next = newchild;
+		if (!parentNode->children) {
+			prevsib = nextsib = NULL;
+		} else if (afterlastchild) {
+			prevsib = parentNode->children == prevsib ? prevsib : parentNode->last;
+		} else {
+			prevsib = parentNode->children == prevsib ? prevsib : NULL;
+		}
 
-		newchild->prev = prevsib;
+		if (prevsib) {
+			fragment->last->next = prevsib->next;
+			if (prevsib->next) {
+				prevsib->next->prev = fragment->last;
+			}
+			prevsib->next = newchild;
+		} else {
+			parentNode->children = newchild;
+			if (nextsib) {
+				fragment->last->next = nextsib;
+				nextsib->prev = fragment->last;
+			}
+		}
 
+		newchild->prev = prevsib;
 		dom_fragment_assign_parent_node(parentNode, fragment);
-		dom_reconcile_ns(prevsib->doc, newchild);
+		dom_reconcile_ns(doc, newchild);
 	}
 
 	xmlFree(fragment);
@@ -337,10 +365,15 @@ void dom_parent_node_before(dom_object *context, zval *nodes, int nodesc)
 {
 	xmlNode *nextsib = dom_object_get_node(context);
 	xmlNodePtr newchild, prevsib, parentNode;
-	xmlNode *fragment;
+	xmlNode *fragment, *afternextsib;
+	xmlDoc *doc;
+	bool beforefirstchild;
 
+	doc = nextsib->doc;
 	prevsib = nextsib->prev;
+	afternextsib = nextsib->next;
 	parentNode = nextsib->parent;
+	beforefirstchild = !prevsib;
 	fragment = dom_zvals_to_fragment(context->document, parentNode, nodes, nodesc);
 
 	if (fragment == NULL) {
@@ -350,24 +383,56 @@ void dom_parent_node_before(dom_object *context, zval *nodes, int nodesc)
 	newchild = fragment->children;
 
 	if (newchild) {
+		if (!parentNode->children) {
+			nextsib = NULL;
+		} else if (beforefirstchild) {
+			nextsib = parentNode->children == nextsib ? nextsib : afternextsib;
+		} else {
+			nextsib = parentNode->children == prevsib ? prevsib->next : nextsib;
+		}
+
 		if (parentNode->children == nextsib) {
 			parentNode->children = newchild;
 		} else {
 			prevsib->next = newchild;
 		}
+
 		fragment->last->next = nextsib;
-		nextsib->prev = fragment->last;
+		if (nextsib) {
+			nextsib->prev = fragment->last;
+		}
 
 		newchild->prev = prevsib;
-
 		dom_fragment_assign_parent_node(parentNode, fragment);
-
-		dom_reconcile_ns(nextsib->doc, newchild);
+		dom_reconcile_ns(doc, newchild);
 	}
 
 	xmlFree(fragment);
 }
 
+bool dom_node_is_argument(dom_object *context, zval *nodes, int nodesc)
+{
+	int i;
+	xmlNode *newNode;
+	zend_class_entry *ce;
+	dom_object *newNodeObj;
+	xmlNode *child = dom_object_get_node(context);
+
+	for (i = 0; i < nodesc; i++) {
+		if (Z_TYPE(nodes[i]) == IS_OBJECT) {
+			ce = Z_OBJCE(nodes[i]);
+			if (instanceof_function(ce, dom_node_class_entry)) {
+				newNodeObj = Z_DOMOBJ_P(&nodes[i]);
+				newNode = dom_object_get_node(newNodeObj);
+				if (child == newNode) {
+					return true;
+				}
+			}
+		}
+	}
+	return false;
+}
+
 void dom_child_node_remove(dom_object *context)
 {
 	xmlNode *child = dom_object_get_node(context);
diff --git a/ext/dom/php_dom.h b/ext/dom/php_dom.h
index 24e1ea646a05d..a39ce6914e3b4 100644
--- a/ext/dom/php_dom.h
+++ b/ext/dom/php_dom.h
@@ -130,6 +130,7 @@ void dom_parent_node_prepend(dom_object *context, zval *nodes, int nodesc);
 void dom_parent_node_append(dom_object *context, zval *nodes, int nodesc);
 void dom_parent_node_after(dom_object *context, zval *nodes, int nodesc);
 void dom_parent_node_before(dom_object *context, zval *nodes, int nodesc);
+bool dom_node_is_argument(dom_object *context, zval *nodes, int nodesc);
 void dom_child_node_remove(dom_object *context);
 
 #define REGISTER_DOM_CLASS(ce, name, parent_ce, funcs, entry) \
diff --git a/ext/dom/tests/bug80602.phpt b/ext/dom/tests/bug80602.phpt
new file mode 100644
index 0000000000000..064e856b60e64
--- /dev/null
+++ b/ext/dom/tests/bug80602.phpt
@@ -0,0 +1,181 @@
+--TEST--
+Bug #80602 (Segfault when using DOMChildNode::before())
+--SKIPIF--
+<?php require_once('skipif.inc'); ?>
+--FILE--
+<?php
+declare(strict_types=1);
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before($target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before($target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before($doc->documentElement->lastChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before($doc->documentElement->firstChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before($target, $doc->documentElement->lastChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before($doc->documentElement->lastChild, $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before($target, $doc->documentElement->firstChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before($doc->documentElement->firstChild, $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before('bar','baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before('bar','baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before($target, 'bar','baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before('bar', $target, 'baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before('bar', 'baz', $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before($target, 'bar','baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before('bar', $target, 'baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before('bar', 'baz', $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before('bar', $target, $doc->documentElement->lastChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before($target, 'bar', $doc->documentElement->lastChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->before($target, $doc->documentElement->lastChild, 'bar');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before('bar', $doc->documentElement->firstChild, $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before($doc->documentElement->firstChild, 'bar', $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->before($doc->documentElement->firstChild, $target, 'bar');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+?>
+--EXPECTF--
+<a>foo<last/></a>
+<a>foo<last/></a>
+<a><last/>foo</a>
+<a>foo<last/></a>
+<a>foo<last/></a>
+<a><last/>foo</a>
+<a><last/>foo</a>
+<a>foo<last/></a>
+<a>barbazfoo<last/></a>
+<a>foobarbaz<last/></a>
+<a>foobarbaz<last/></a>
+<a>barfoobaz<last/></a>
+<a>barbazfoo<last/></a>
+<a>foo<last/>barbaz</a>
+<a>foobar<last/>baz</a>
+<a>foobarbaz<last/></a>
+<a>barfoo<last/></a>
+<a>foobar<last/></a>
+<a>foo<last/>bar</a>
+<a>barfoo<last/></a>
+<a>foobar<last/></a>
+<a>foo<last/>bar</a>
+
diff --git a/ext/dom/tests/bug80602_2.phpt b/ext/dom/tests/bug80602_2.phpt
new file mode 100644
index 0000000000000..9d697c64172a0
--- /dev/null
+++ b/ext/dom/tests/bug80602_2.phpt
@@ -0,0 +1,180 @@
+--TEST--
+Bug #80602 (Segfault when using DOMChildNode::after())
+--SKIPIF--
+<?php require_once('skipif.inc'); ?>
+--FILE--
+<?php
+declare(strict_types=1);
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after($target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after($target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after($doc->documentElement->lastChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after($doc->documentElement->firstChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after($target, $doc->documentElement->lastChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after($doc->documentElement->lastChild, $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after($target, $doc->documentElement->firstChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after($doc->documentElement->firstChild, $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after('bar','baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after('bar','baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after($target, 'bar','baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after('bar', $target, 'baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after('bar', 'baz', $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after($target, 'bar','baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after('bar', $target, 'baz');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after('bar', 'baz', $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after('bar', $target, $doc->documentElement->lastChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after($target, 'bar', $doc->documentElement->lastChild);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->firstChild;
+$target->after($target, $doc->documentElement->lastChild, 'bar');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after('bar', $doc->documentElement->firstChild, $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after($doc->documentElement->firstChild, 'bar', $target);
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+
+$doc = new \DOMDocument();
+$doc->loadXML('<a>foo<last/></a>');
+$target = $doc->documentElement->lastChild;
+$target->after($doc->documentElement->firstChild, $target, 'bar');
+echo $doc->saveXML($doc->documentElement).PHP_EOL;
+
+?>
+--EXPECTF--
+<a>foo<last/></a>
+<a>foo<last/></a>
+<a>foo<last/></a>
+<a><last/>foo</a>
+<a>foo<last/></a>
+<a><last/>foo</a>
+<a><last/>foo</a>
+<a>foo<last/></a>
+<a>foobarbaz<last/></a>
+<a>foo<last/>barbaz</a>
+<a>foobarbaz<last/></a>
+<a>barfoobaz<last/></a>
+<a>barbazfoo<last/></a>
+<a>foo<last/>barbaz</a>
+<a>foobar<last/>baz</a>
+<a>foobarbaz<last/></a>
+<a>barfoo<last/></a>
+<a>foobar<last/></a>
+<a>foo<last/>bar</a>
+<a>barfoo<last/></a>
+<a>foobar<last/></a>
+<a>foo<last/>bar</a>
diff --git a/ext/dom/tests/bug81642.phpt b/ext/dom/tests/bug81642.phpt
new file mode 100644
index 0000000000000..b1581cfdb14ba
--- /dev/null
+++ b/ext/dom/tests/bug81642.phpt
@@ -0,0 +1,32 @@
+--TEST--
+Bug #81642 DOMChildNode::replaceWith() bug when replacing a node with itself.
+--SKIPIF--
+<?php require_once('skipif.inc'); ?>
+--FILE--
+<?php
+require_once("dom_test.inc");
+
+$doc = new DOMDocument;
+$headNode = $doc->createElement("head");
+$doc->appendChild($headNode);
+$titleNode = $doc->createElement("title");
+$headNode->appendChild($titleNode);
+$titleNode->replaceWith($titleNode);
+echo $doc->saveXML().PHP_EOL;
+
+$doc = new DOMDocument;
+$headNode = $doc->createElement("head");
+$doc->appendChild($headNode);
+$titleNode = $doc->createElement("title");
+$headNode->appendChild($titleNode);
+$titleNode->replaceWith($titleNode, 'foo');
+echo $doc->saveXML().PHP_EOL;
+
+?>
+--EXPECT--
+<?xml version="1.0"?>
+<head><title/></head>
+
+<?xml version="1.0"?>
+<head><title/>foo</head>
+
diff --git a/ext/dom/tests/gh9142.phpt b/ext/dom/tests/gh9142.phpt
new file mode 100644
index 0000000000000..bae8cc2f3ff68
--- /dev/null
+++ b/ext/dom/tests/gh9142.phpt
@@ -0,0 +1,40 @@
+--TEST--
+GitHub #9142 (DOMChildNode replaceWith() double-free error when replacing elements not separated by any whitespace)
+--SKIPIF--
+<?php require_once('skipif.inc'); ?>
+--FILE--
+<?php
+$a = '<var>One</var> <var>Two</var>'; // Works fine
+($domA = new DOMDocument('1.0', 'UTF-8'))->loadHTML($a);
+foreach ((new DOMXPath($domA))->query('//var') as $var) {
+    $var->replaceWith($domA->createElement('p', $var->nodeValue));
+}
+var_dump($domA->saveHTML());
+
+
+$b = '<var>One</var><var>Two</var>'; // Causes a 'double free' error
+($domB = new DOMDocument('1.0', 'UTF-8'))->loadHTML($b);
+foreach ((new DOMXPath($domB))->query('//var') as $var) {
+    $var->replaceWith($domB->createElement('p', $var->nodeValue));
+}
+var_dump($domB->saveHTML());
+
+
+$document = '<var>One</var><var>Two</var>';
+($dom = new DOMDocument('1.0', 'UTF-8'))->loadHTML($document);
+foreach ((new DOMXPath($dom))->query('//var') as $var) {
+	$var->after($dom->createElement('p', $var->nodeValue));
+	$var->remove();
+}
+var_dump($dom->saveHTML());
+?>
+--EXPECT--
+string(155) "<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
+<html><body><p>One</p> <p>Two</p></body></html>
+"
+string(154) "<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
+<html><body><p>One</p><p>Two</p></body></html>
+"
+string(154) "<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
+<html><body><p>One</p><p>Two</p></body></html>
+"