diff --git a/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConverter.cs b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConverter.cs
index 382962a7f..d2ccafcfd 100644
--- a/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConverter.cs
+++ b/src/Squidex.Infrastructure.MongoDb/MongoDb/BsonJsonConverter.cs
@@ -82,15 +82,15 @@ namespace Squidex.Infrastructure.MongoDb
                 case JTokenType.Undefined:
                     return BsonUndefined.Value;
                 case JTokenType.Date:
-                    return BsonValue.Create(((JValue)source).Value.ToString());
+                    return BsonValue.Create(((JValue)source).ToString("yyyy-MM-ddTHH:mm:ssK"));
                 case JTokenType.Bytes:
                     return BsonValue.Create(((JValue)source).Value);
                 case JTokenType.Guid:
-                    return BsonValue.Create(((JValue)source).Value.ToString());
+                    return BsonValue.Create(((JValue)source).ToString());
                 case JTokenType.Uri:
-                    return BsonValue.Create(((JValue)source).Value.ToString());
+                    return BsonValue.Create(((JValue)source).ToString());
                 case JTokenType.TimeSpan:
-                    return BsonValue.Create(((JValue)source).Value.ToString());
+                    return BsonValue.Create(((JValue)source).ToString());
             }
 
             throw new NotSupportedException($"Cannot convert {source.GetType()} to Bson.");
diff --git a/tests/Squidex.Infrastructure.Tests/MongoDb/BsonConverterTests.cs b/tests/Squidex.Infrastructure.Tests/MongoDb/BsonConverterTests.cs
index 45e96edd2..f943ffb91 100644
--- a/tests/Squidex.Infrastructure.Tests/MongoDb/BsonConverterTests.cs
+++ b/tests/Squidex.Infrastructure.Tests/MongoDb/BsonConverterTests.cs
@@ -125,6 +125,18 @@ namespace Squidex.Infrastructure.MongoDb
             target.ShouldBeEquivalentTo(source);
         }
 
+        [Fact]
+        public void Should_serialize_to_iso()
+        {
+            source.DateTime = new DateTime(2012, 12, 12, 12, 12, 12, DateTimeKind.Utc);
+            source.DateTimeOffset = new DateTime(2012, 12, 12, 12, 12, 12, DateTimeKind.Utc);
+
+            var target = JObject.FromObject(source).ToBson();
+
+            Assert.Equal("2012-12-12T12:12:12Z", target["DateTime"].ToString());
+            Assert.Equal("2012-12-12T12:12:12Z", target["DateTimeOffset"].ToString());
+        }
+
         [Fact]
         public void Should_write_problematic_object()
         {