diff --git a/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/GeoJsonConverterFactory.cs b/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/GeoJsonConverterFactory.cs
index c966f91..7a3a94d 100644
--- a/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/GeoJsonConverterFactory.cs
+++ b/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/GeoJsonConverterFactory.cs
@@ -190,6 +190,7 @@ public GeoJsonConverterFactory(GeometryFactory factory, bool writeGeometryBBox,
         public override bool CanConvert(Type typeToConvert)
         {
             return GeometryTypes.Contains(typeToConvert)
+                   || typeToConvert == typeof(Envelope)
                    || typeof(IFeature).IsAssignableFrom(typeToConvert)
                    || typeToConvert == typeof(FeatureCollection)
                    || typeof(IAttributesTable).IsAssignableFrom(typeToConvert);
@@ -200,6 +201,8 @@ public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializer
         {
             if (GeometryTypes.Contains(typeToConvert))
                 return new StjGeometryConverter(_factory, _writeGeometryBBox, _ringOrientationOption);
+            if (typeToConvert == typeof(Envelope))
+                return new StjEnvelopeConverter();
             if (typeToConvert == typeof(FeatureCollection))
                 return new StjFeatureCollectionConverter(_writeGeometryBBox);
             if (typeof(IFeature).IsAssignableFrom(typeToConvert))
diff --git a/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/StjEnvelopeConverter.cs b/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/StjEnvelopeConverter.cs
new file mode 100644
index 0000000..e3c866b
--- /dev/null
+++ b/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/StjEnvelopeConverter.cs
@@ -0,0 +1,69 @@
+using NetTopologySuite.Geometries;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace NetTopologySuite.IO.Converters
+{
+    internal class StjEnvelopeConverter : JsonConverter<Envelope>
+    {
+        public override Envelope Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        {
+            Envelope res = null;
+
+            if (reader.TokenType == JsonTokenType.Null)
+            {
+                // #57: callers expect us to have read past the last token
+                reader.Read();
+            }
+            else
+            {
+                reader.ReadToken(JsonTokenType.StartArray);
+
+                double minX = reader.GetDouble();
+                reader.Read();
+                double minY = reader.GetDouble();
+                reader.Read();
+                double maxX = reader.GetDouble();
+                reader.Read();
+                double maxY = reader.GetDouble();
+                reader.Read();
+
+                if (reader.TokenType == JsonTokenType.Number)
+                {
+                    maxX = maxY;
+                    maxY = reader.GetDouble();
+                    reader.Read();
+                    reader.Read();
+                }
+
+                reader.ReadToken(JsonTokenType.EndArray);
+
+                res = new Envelope(minX, maxX, minY, maxY);
+            }
+
+            //reader.Read(); // move away from array end
+            return res;
+        }
+
+        public override void Write(Utf8JsonWriter writer, Envelope value, JsonSerializerOptions options)
+        {
+            // if we don't want to write "null" bounding boxes, bail out.
+            if (value?.IsNull != false)
+            {
+                writer.WriteNullValue();
+
+                return;
+            }
+
+            writer.WriteStartArray();
+            writer.WriteNumberValue(value.MinX);
+            writer.WriteNumberValue(value.MinY);
+            writer.WriteNumberValue(value.MaxX);
+            writer.WriteNumberValue(value.MaxY);
+            writer.WriteEndArray();
+        }
+    }
+}
diff --git a/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/StjGeometryConverter.Envelope.cs b/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/StjGeometryConverter.Envelope.cs
index 75e5004..bda42da 100644
--- a/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/StjGeometryConverter.Envelope.cs
+++ b/src/NetTopologySuite.IO.GeoJSON4STJ/Converters/StjGeometryConverter.Envelope.cs
@@ -1,6 +1,4 @@
-using System;
-using System.Text.Json;
-using System.Text.Json.Serialization;
+using System.Text.Json;
 using NetTopologySuite.Geometries;
 
 namespace NetTopologySuite.IO.Converters
@@ -10,7 +8,6 @@ internal partial class StjGeometryConverter
         internal static Envelope ReadBBox(ref Utf8JsonReader reader, JsonSerializerOptions options)
         {
             Envelope res = null;
-
             if (reader.TokenType == JsonTokenType.Null)
             {
                 // #57: callers expect us to have read past the last token
@@ -18,28 +15,7 @@ internal static Envelope ReadBBox(ref Utf8JsonReader reader, JsonSerializerOptio
             }
             else
             {
-                reader.ReadToken(JsonTokenType.StartArray);
-
-                double minX = reader.GetDouble();
-                reader.Read();
-                double minY = reader.GetDouble();
-                reader.Read();
-                double maxX = reader.GetDouble();
-                reader.Read();
-                double maxY = reader.GetDouble();
-                reader.Read();
-
-                if (reader.TokenType == JsonTokenType.Number)
-                {
-                    maxX = maxY;
-                    maxY = reader.GetDouble();
-                    reader.Read();
-                    reader.Read();
-                }
-
-                reader.ReadToken(JsonTokenType.EndArray);
-
-                res = new Envelope(minX, maxX, minY, maxY);
+                res = JsonSerializer.Deserialize<Envelope>(ref reader, options);
             }
 
             //reader.Read(); // move away from array end
@@ -66,13 +42,7 @@ internal static void WriteBBox(Utf8JsonWriter writer, Envelope value, JsonSerial
             }
 
             writer.WritePropertyName("bbox");
-
-            writer.WriteStartArray();
-            writer.WriteNumberValue(value.MinX);
-            writer.WriteNumberValue(value.MinY);
-            writer.WriteNumberValue(value.MaxX);
-            writer.WriteNumberValue(value.MaxY);
-            writer.WriteEndArray();
+            JsonSerializer.Serialize(writer, value, typeof(Envelope), options);
         }
     }
 }