diff --git a/Ooui/JsonConvert.cs b/Ooui/JsonConvert.cs
index 1eddd06..0fd22b4 100644
--- a/Ooui/JsonConvert.cs
+++ b/Ooui/JsonConvert.cs
@@ -2,7 +2,7 @@
 
 namespace Ooui
 {
-    class JsonConvert
+    public class JsonConvert
     {
         public static void WriteJsonString (System.IO.TextWriter w, string s)
         {
@@ -36,60 +36,44 @@ namespace Ooui
 
         public static void WriteJsonValue (System.IO.TextWriter w, object value)
         {
-            if (value == null) {
-                w.Write ("null");
-                return;
+            switch(value) {
+                case string s:
+                    WriteJsonString (w, s);
+                    break;
+                case Array a:
+                    w.Write ('[');
+                    var head = "";
+                    foreach (var o in a) {
+                        w.Write (head);
+                        WriteJsonValue (w, o);
+                        head = ",";
+                    }
+                    w.Write (']');
+                    break;
+                case EventTarget e:
+                    w.Write ('\"');
+                    w.Write (e.Id);
+                    w.Write ('\"');
+                    break;
+                case Color c:
+                    WriteJsonString (w, c.ToString ());
+                    break;
+                case double d:
+                    w.Write (d.ToString (System.Globalization.CultureInfo.InvariantCulture));
+                    break;
+                case int i:
+                    w.Write (i.ToString (System.Globalization.CultureInfo.InvariantCulture));
+                    break;
+                case float f:
+                    w.Write (f.ToString (System.Globalization.CultureInfo.InvariantCulture));
+                    break;
+                case null:
+                    w.Write ("null");
+                    break;
+                default:
+                    w.Write (Newtonsoft.Json.JsonConvert.SerializeObject (value));
+                    break;
             }
-            var s = value as string;
-            if (s != null) {
-                WriteJsonString (w, s);
-                return;
-            }
-
-            var a = value as Array;
-            if (a != null) {
-                w.Write ('[');
-                var head = "";
-                foreach (var o in a) {
-                    w.Write (head);
-                    WriteJsonValue (w, o);
-                    head = ",";
-                }
-                w.Write (']');
-                return;
-            }
-
-            var e = value as EventTarget;
-            if (e != null) {
-                w.Write ('\"');
-                w.Write (e.Id);
-                w.Write ('\"');
-                return;
-            }
-
-            if (value is Color) {
-                WriteJsonString (w, ((Color)value).ToString ());
-                return;
-            }
-
-            var icult = System.Globalization.CultureInfo.InvariantCulture;
-
-            if (value is double) {
-                w.Write (((double)value).ToString (icult));
-                return;
-            }
-
-            if (value is int) {
-                w.Write (((int)value).ToString (icult));
-                return;
-            }
-
-            if (value is float) {
-                w.Write (((float)value).ToString (icult));
-                return;
-            }
-
-            w.Write (Newtonsoft.Json.JsonConvert.SerializeObject (value));
         }
 
         public static string SerializeObject (object value)
diff --git a/Tests/JsonTests.cs b/Tests/JsonTests.cs
index 37c637a..5ac373f 100644
--- a/Tests/JsonTests.cs
+++ b/Tests/JsonTests.cs
@@ -11,6 +11,7 @@ using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Ooui;
 using System.IO;
 using System.Text.RegularExpressions;
+using System.Text;
 
 namespace Tests
 {
@@ -50,5 +51,95 @@ namespace Tests
                              "{\"m\":\"call\",\"id\":\"⦙\",\"k\":\"insertBefore\",\"v\":[\"⦙\",null]}" +
                              "{\"m\":\"listen\",\"id\":\"⦙\",\"k\":\"click\"}", NoId (sw.ToString ()));
         }
+
+        [TestMethod]
+        public void JsonConvertValueNull ()
+        {
+            TextWriter w = new InMemoryTextWriter ();
+            JsonConvert.WriteJsonValue (w, null);
+            Assert.AreEqual ("null", w.ToString ());
+        }
+
+        [TestMethod]
+        public void JsonConvertValueString ()
+        {
+            TextWriter w = new InMemoryTextWriter ();
+            JsonConvert.WriteJsonValue (w, "string");
+            Assert.AreEqual ("\"string\"", w.ToString ());
+        }
+
+        [TestMethod]
+        public void JsonConvertValueArray ()
+        {
+            TextWriter w = new InMemoryTextWriter();
+            JsonConvert.WriteJsonValue (w, new[] { 1, 2, 3 });
+            Assert.AreEqual("[1,2,3]", w.ToString ());
+        }
+
+        [TestMethod]
+        public void JsonConvertValueEventTarget ()
+        {
+            TextWriter w = new InMemoryTextWriter ();
+            var textNode = new TextNode ();
+            JsonConvert.WriteJsonValue (w, textNode);
+            Assert.AreEqual ($"\"{textNode.Id}\"", w.ToString ());
+        }
+
+        [TestMethod]
+        public void JsonConvertValueColor ()
+        {
+            TextWriter w = new InMemoryTextWriter ();
+            var color = new Color (255, 255, 255, 0);
+            JsonConvert.WriteJsonValue (w, color);
+            Assert.AreEqual ("\"rgba(255,255,255,0)\"", w.ToString ());
+        }
+
+        [TestMethod]
+        public void JsonConvertValueDouble ()
+        {
+            TextWriter w = new InMemoryTextWriter ();
+            double d = 4.5;
+            JsonConvert.WriteJsonValue (w, d);
+            Assert.AreEqual ("4.5", w.ToString ());
+        }
+
+        [TestMethod]
+        public void JsonConvertValueInt ()
+        {
+            TextWriter w = new InMemoryTextWriter ();
+            int i = 45;
+            JsonConvert.WriteJsonValue (w, i);
+            Assert.AreEqual ("45", w.ToString ());
+        }
+
+        [TestMethod]
+        public void JsonConvertValueFloat ()
+        {
+            TextWriter w = new InMemoryTextWriter ();
+            float f = 45.5f;
+            JsonConvert.WriteJsonValue (w, f);
+            Assert.AreEqual ("45.5", w.ToString ());
+        }
+
+        [TestMethod]
+        public void JsonConvertValueOther ()
+        {
+            TextWriter w = new InMemoryTextWriter ();
+            JsonConvert.WriteJsonValue (w, new { foo = "bar" });
+            Assert.AreEqual ("{\"foo\":\"bar\"}", w.ToString ());
+        }
+
+        class InMemoryTextWriter : TextWriter
+        {
+            private StringBuilder builder = new StringBuilder ();
+
+            public InMemoryTextWriter() { }
+
+            public override void Write(char value) => builder.Append(value);
+
+            public override string ToString() => builder.ToString();
+
+            public override Encoding Encoding => Encoding.UTF8;
+        }
     }
 }