diff --git a/src/browser/webapi/DOMImplementation.zig b/src/browser/webapi/DOMImplementation.zig
index 1e0a44b69..cce49bd0e 100644
--- a/src/browser/webapi/DOMImplementation.zig
+++ b/src/browser/webapi/DOMImplementation.zig
@@ -50,6 +50,7 @@ pub fn createHTMLDocument(_: *const DOMImplementation, title: ?js.NullableString
     const document = (try frame._factory.document(Node.Document.HTMLDocument{ ._proto = undefined })).asDocument();
     document._ready_state = .complete;
     document._url = "about:blank";
+    document._charset = "UTF-8";
 
     {
         const doctype = try frame._factory.node(DocumentType{
@@ -101,6 +102,7 @@ pub fn createDocument(_: *const DOMImplementation, namespace_nullable: js.Nullab
     // Create XML Document
     const document = (try frame._factory.document(Node.Document.XMLDocument{ ._proto = undefined })).asDocument();
     document._url = "about:blank";
+    document._charset = "UTF-8";
     // Per spec the content type depends on the requested namespace.
     document._content_type = blk: {
         const ns = namespace_ orelse break :blk "application/xml";
diff --git a/src/browser/webapi/Document.zig b/src/browser/webapi/Document.zig
index b34de50ba..ec32cdc3b 100644
--- a/src/browser/webapi/Document.zig
+++ b/src/browser/webapi/Document.zig
@@ -56,6 +56,9 @@ _frame: ?*Frame = null,
 _url: ?[:0]const u8 = null, // URL for documents created via DOMImplementation (about:blank)
 // content type override for documents created via DOMImplementation.createDocument
 _content_type: ?[]const u8 = null,
+// encoding override: documents synthesized by script (createHTMLDocument,
+// createDocument) are UTF-8 regardless of the frame's encoding
+_charset: ?[]const u8 = null,
 _ready_state: ReadyState = .loading,
 _current_script: ?*Element.Html.Script = null,
 _elements_by_id: std.StringHashMapUnmanaged(*Element) = .empty,
@@ -159,6 +162,14 @@ pub fn setLocation(self: *Document, url: [:0]const u8) !void {
     return frame.scheduleNavigation(url, .{ .reason = .script, .kind = .{ .push = null } }, .{ .script = frame });
 }
 
+pub fn getCharset(self: *const Document) []const u8 {
+    if (self._charset) |charset| {
+        return charset;
+    }
+    const doc_frame = self._frame orelse return "UTF-8";
+    return doc_frame.charset;
+}
+
 pub fn getContentType(self: *const Document) []const u8 {
     if (self._content_type) |content_type| {
         return content_type;
@@ -1417,6 +1428,7 @@ pub const JsApi = struct {
         return frame._factory.node(Document{
             ._proto = undefined,
             ._type = .generic,
+            ._charset = "UTF-8",
         });
     }
 
@@ -1508,8 +1520,7 @@ pub const JsApi = struct {
     pub const compatMode = bridge.property("CSS1Compat", .{ .template = false });
 
     fn getCharacterSet(self: *const Document) []const u8 {
-        const doc_frame = self._frame orelse return "UTF-8";
-        return doc_frame.charset;
+        return self.getCharset();
     }
     pub const referrer = bridge.property("", .{ .template = false });
 
diff --git a/src/browser/webapi/Node.zig b/src/browser/webapi/Node.zig
index 2151e1d14..bd0157a6f 100644
--- a/src/browser/webapi/Node.zig
+++ b/src/browser/webapi/Node.zig
@@ -582,7 +582,11 @@ pub const ResolveURLOpts = struct {
 pub fn resolveURL(self: *const Node, url: anytype, frame: *Frame, opts: ResolveURLOpts) ![:0]const u8 {
     const owner_frame = self.ownerFrame(frame);
     const allocator = opts.allocator orelse frame.call_arena;
-    return URL.resolve(allocator, owner_frame.base(), url, .{ .encoding = owner_frame.charset });
+    // The owning document's encoding, not the frame's: script-created
+    // documents (e.g. createHTMLDocument) are always UTF-8.
+    const doc: ?*const Document = if (self._type == .document) self._type.document else self.ownerDocument(frame);
+    const encoding = if (doc) |d| d.getCharset() else owner_frame.charset;
+    return URL.resolve(allocator, owner_frame.base(), url, .{ .encoding = encoding });
 }
 
 // Same as `resolveURL` but can't return `TypeError`, this is needed for multiple