diff --git a/src/browser/js/Local.zig b/src/browser/js/Local.zig
index e9d9d9d9..4c5d1fba 100644
--- a/src/browser/js/Local.zig
+++ b/src/browser/js/Local.zig
@@ -453,6 +453,13 @@ pub fn jsValueToZig(self: *const Local, comptime T: type, js_val: js.Value) !T {
                 return js_val;
             }
 
+            if (comptime o.child == js.NullableString) {
+                if (js_val.isUndefined()) {
+                    return null;
+                }
+                return .{ .value = try js_val.toStringSlice() };
+            }
+
             if (comptime o.child == js.Object) {
                 return js.Object{
                     .local = self,
diff --git a/src/browser/js/js.zig b/src/browser/js/js.zig
index 112cc596..9415b717 100644
--- a/src/browser/js/js.zig
+++ b/src/browser/js/js.zig
@@ -168,6 +168,16 @@ pub fn ArrayBufferRef(comptime kind: ArrayType) type {
     };
 }
 
+// If a WebAPI takes a []const u8, then we'll coerce any JS value to that string
+// so null -> "null". But if a WebAPI takes an optional string, ?[]const u8,
+// how should we handle null? If the parameter _isn't_ passed, then it's obvious
+// that it should be null, but what if `null` is passed? It's ambiguous, should
+// that be null, or "null"? It could depend on the api. So, `null` passed to
+// ?[]const u8 will be `null`. If you want it to be "null", use a `.js.NullableString`.
+pub const NullableString = struct {
+    value: []const u8,
+};
+
 pub const Exception = struct {
     local: *const Local,
     handle: *const v8.Value,
diff --git a/src/browser/tests/cdata/comment.html b/src/browser/tests/cdata/comment.html
index 453da384..e1e0e0a4 100644
--- a/src/browser/tests/cdata/comment.html
+++ b/src/browser/tests/cdata/comment.html
@@ -4,4 +4,6 @@
 <script id=comment>
   testing.expectEqual('', new Comment().data);
   testing.expectEqual('over 9000! ', new Comment('over 9000! ').data);
+
+  testing.expectEqual('null', new Comment(null).data);
 </script>
diff --git a/src/browser/tests/cdata/text/text.html b/src/browser/tests/cdata/text.html
similarity index 81%
rename from src/browser/tests/cdata/text/text.html
rename to src/browser/tests/cdata/text.html
index 9c5ac3d1..1278deb0 100644
--- a/src/browser/tests/cdata/text/text.html
+++ b/src/browser/tests/cdata/text.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <a id="link" href="foo" class="ok">OK</a>
 
-<script src="../../testing.js"></script>
+<script src="../testing.js"></script>
 <script id=text>
   let t = new Text('foo');
   testing.expectEqual('foo', t.data);
@@ -16,4 +16,7 @@
   let split = text.splitText('OK'.length);
   testing.expectEqual(' modified', split.data);
   testing.expectEqual('OK', text.data);
+
+    let x = new Text(null);
+    testing.expectEqual("null", x.data);
 </script>
diff --git a/src/browser/tests/domimplementation.html b/src/browser/tests/domimplementation.html
index 1d524e0d..302db88a 100644
--- a/src/browser/tests/domimplementation.html
+++ b/src/browser/tests/domimplementation.html
@@ -108,6 +108,20 @@
   }
 </script>
 
+<script id=createHTMLDocument_nulll_title>
+  {
+    const impl = document.implementation;
+    const doc = impl.createHTMLDocument(null);
+
+    testing.expectEqual('null', doc.title);
+
+    // Should have title element in head
+    const titleElement = doc.head.querySelector('title');
+    testing.expectEqual(true, titleElement !== null);
+    testing.expectEqual('null', titleElement.textContent);
+  }
+</script>
+
 <script id=createHTMLDocument_structure>
   {
     const impl = document.implementation;
diff --git a/src/browser/webapi/DOMImplementation.zig b/src/browser/webapi/DOMImplementation.zig
index 2ad592eb..51dd1b32 100644
--- a/src/browser/webapi/DOMImplementation.zig
+++ b/src/browser/webapi/DOMImplementation.zig
@@ -31,7 +31,7 @@ pub fn createDocumentType(_: *const DOMImplementation, qualified_name: []const u
     return DocumentType.init(qualified_name, public_id, system_id, page);
 }
 
-pub fn createHTMLDocument(_: *const DOMImplementation, title: ?[]const u8, page: *Page) !*Document {
+pub fn createHTMLDocument(_: *const DOMImplementation, title: ?js.NullableString, page: *Page) !*Document {
     const document = (try page._factory.document(Node.Document.HTMLDocument{ ._proto = undefined })).asDocument();
     document._ready_state = .complete;
     document._url = "about:blank";
@@ -55,7 +55,7 @@ pub fn createHTMLDocument(_: *const DOMImplementation, title: ?[]const u8, page:
     if (title) |t| {
         const title_node = try page.createElementNS(.html, "title", null);
         _ = try head_node.appendChild(title_node, page);
-        const text_node = try page.createTextNode(t);
+        const text_node = try page.createTextNode(t.value);
         _ = try title_node.appendChild(text_node, page);
     }
 
diff --git a/src/browser/webapi/cdata/Comment.zig b/src/browser/webapi/cdata/Comment.zig
index 39282d69..ff8ef234 100644
--- a/src/browser/webapi/cdata/Comment.zig
+++ b/src/browser/webapi/cdata/Comment.zig
@@ -25,8 +25,8 @@ const Comment = @This();
 
 _proto: *CData,
 
-pub fn init(content: ?[]const u8, page: *Page) !*Comment {
-    const node = try page.createComment(content orelse "");
+pub fn init(str: ?js.NullableString, page: *Page) !*Comment {
+    const node = try page.createComment(if (str) |s| s.value else "");
     return node.as(Comment);
 }
 
@@ -42,3 +42,8 @@ pub const JsApi = struct {
 
     pub const constructor = bridge.constructor(Comment.init, .{});
 };
+
+const testing = @import("../../../testing.zig");
+test "WebApi: CData.Text" {
+    try testing.htmlRunner("cdata/comment.html", .{});
+}
diff --git a/src/browser/webapi/cdata/Text.zig b/src/browser/webapi/cdata/Text.zig
index 310edb32..6c385c41 100644
--- a/src/browser/webapi/cdata/Text.zig
+++ b/src/browser/webapi/cdata/Text.zig
@@ -16,6 +16,7 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+const js = @import("../../js/js.zig");
 const Page = @import("../../Page.zig");
 const CData = @import("../CData.zig");
 
@@ -23,8 +24,8 @@ const Text = @This();
 
 _proto: *CData,
 
-pub fn init(str: ?[]const u8, page: *Page) !*Text {
-    const node = try page.createTextNode(str orelse "");
+pub fn init(str: ?js.NullableString, page: *Page) !*Text {
+    const node = try page.createTextNode(if (str) |s| s.value else "");
     return node.as(Text);
 }
 
@@ -56,13 +57,7 @@ pub fn splitText(self: *Text, offset: usize, page: *Page) !*Text {
     return new_text;
 }
 
-const testing = @import("../../../testing.zig");
-test "WebApi: CData.Text" {
-    try testing.htmlRunner("cdata/text", .{});
-}
-
 pub const JsApi = struct {
-    const js = @import("../../js/js.zig");
     pub const bridge = js.Bridge(Text);
 
     pub const Meta = struct {
