diff --git a/src/main/scala/io/epiphanous/flinkrunner/serde/AvroJsonSerializer.scala b/src/main/scala/io/epiphanous/flinkrunner/serde/AvroJsonSerializer.scala
index 35c6c60..8aadbbf 100644
--- a/src/main/scala/io/epiphanous/flinkrunner/serde/AvroJsonSerializer.scala
+++ b/src/main/scala/io/epiphanous/flinkrunner/serde/AvroJsonSerializer.scala
@@ -1,8 +1,8 @@
 package io.epiphanous.flinkrunner.serde
 
 import com.fasterxml.jackson.core.JsonGenerator
-import com.fasterxml.jackson.databind.ser.std.StdSerializer
 import com.fasterxml.jackson.databind.{JsonSerializer, SerializerProvider}
+import com.fasterxml.jackson.databind.ser.std.StdSerializer
 import com.typesafe.scalalogging.LazyLogging
 import org.apache.avro.Schema
 import org.apache.avro.Schema.Type._
@@ -12,6 +12,7 @@ import org.apache.flink.api.scala.createTypeInformation
 
 import scala.annotation.tailrec
 import scala.collection.JavaConverters._
+import scala.collection.convert.ImplicitConversions.`map AsScala`
 
 /** A simple custom jackson serializer to handle serializing avro records
   * (Generic or Specific)
@@ -61,6 +62,7 @@ class AvroJsonSerializer
         }
         gen.writeEndArray()
       case (MAP, map: Map[String, _] @unchecked) =>
+      case (MAP, map: scala.collection.convert.Wrappers.MapWrapper[String,Any] @unchecked) =>
         gen.writeObjectFieldStart(name)
         map.foreach { case (k, e) =>
           gen.writeFieldName(k)
@@ -95,13 +97,13 @@ class AvroJsonSerializer
       case (BOOLEAN, boolean: Boolean)           =>
         gen.writeBooleanField(name, boolean)
       case _                                     =>
-        gen.writeFieldName(name)
-        provider
-          .findValueSerializer(
-            implicitly[TypeInformation[T]].getTypeClass
-          )
-          .asInstanceOf[JsonSerializer[T]]
-          .serialize(value, gen, provider)
+          gen.writeFieldName(name)
+          provider
+            .findValueSerializer(
+              implicitly[TypeInformation[T]].getTypeClass
+            )
+            .asInstanceOf[JsonSerializer[T]]
+            .serialize(value, gen, provider)
     }
   }
 
@@ -122,7 +124,7 @@ class AvroJsonSerializer
           _serializeElement(e, schema.getElementType, gen, provider)
         }
       case (MAP, _)                        => gen.writeObject(value)
-      case (UNION, _)                      => // todo
+      case (UNION, _)                      => gen.writeString(value.toString)
       case (STRING, string: String)        => gen.writeString(string)
       case (INT, int: Int)                 => gen.writeNumber(int)
       case (LONG, long: Long)              => gen.writeNumber(long)