diff --git a/Libraries/LibHTML/Parser/HTMLParser.cpp b/Libraries/LibHTML/Parser/HTMLParser.cpp
index bf1accfb75..c8275cd33c 100644
--- a/Libraries/LibHTML/Parser/HTMLParser.cpp
+++ b/Libraries/LibHTML/Parser/HTMLParser.cpp
@@ -318,13 +318,13 @@ RefPtr<DocumentFragment> parse_html_fragment(Document& document, const StringVie
     return fragment;
 }
 
-NonnullRefPtr<Document> parse_html_document(const StringView& html, const URL& url)
+RefPtr<Document> parse_html_document(const StringView& html, const URL& url)
 {
     auto document = adopt(*new Document);
     document->set_url(url);
 
-    bool success = parse_html_document(html, *document, *document);
-    ASSERT(success);
+    if (!parse_html_document(html, *document, *document))
+        return nullptr;
 
     document->fixup();
 
diff --git a/Libraries/LibHTML/Parser/HTMLParser.h b/Libraries/LibHTML/Parser/HTMLParser.h
index 46dc22428a..8b06ce2842 100644
--- a/Libraries/LibHTML/Parser/HTMLParser.h
+++ b/Libraries/LibHTML/Parser/HTMLParser.h
@@ -5,5 +5,5 @@
 
 class DocumentFragment;
 
-NonnullRefPtr<Document> parse_html_document(const StringView&, const URL& = URL());
+RefPtr<Document> parse_html_document(const StringView&, const URL& = URL());
 RefPtr<DocumentFragment> parse_html_fragment(Document&, const StringView&);