diff --git a/src/main/java/ch/psi/daq/queryrest/config/QueryRestConfig.java b/src/main/java/ch/psi/daq/queryrest/config/QueryRestConfig.java
index 151b9be..3ef9163 100644
--- a/src/main/java/ch/psi/daq/queryrest/config/QueryRestConfig.java
+++ b/src/main/java/ch/psi/daq/queryrest/config/QueryRestConfig.java
@@ -41,6 +41,7 @@ import ch.psi.daq.query.model.QueryField;
 import ch.psi.daq.query.model.impl.AbstractQuery;
 import ch.psi.daq.queryrest.controller.validator.QueryValidator;
 import ch.psi.daq.queryrest.model.PropertyFilterMixin;
+import ch.psi.daq.queryrest.response.JsonByteArraySerializer;
 import ch.psi.daq.queryrest.response.JsonStreamSerializer;
 import ch.psi.daq.queryrest.response.ResponseStreamWriter;
 
@@ -75,16 +76,16 @@ public class QueryRestConfig extends WebMvcConfigurerAdapter {
     */
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
-       final MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
-       /**
+      final MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
+      /**
        * This is necessary so that the message conversion uses the configured object mapper.
        * Otherwise, a separate object mapper is instantiated for Springs message conversion.
        */
-       converter.setObjectMapper(objectMapper());
-       converters.add(converter);
-       super.configureMessageConverters(converters);
+      converter.setObjectMapper(objectMapper());
+      converters.add(converter);
+      super.configureMessageConverters(converters);
    }
-   
+
    @Bean
    public ObjectMapper objectMapper() {
       ObjectMapper mapper = new ObjectMapper();
@@ -110,9 +111,14 @@ public class QueryRestConfig extends WebMvcConfigurerAdapter {
       module.addSerializer(new JsonStreamSerializer());
       mapper.registerModule(module);
 
+      // by default, byte[] are written as String
+      module = new SimpleModule("byte[]", Version.unknownVersion());
+      module.addSerializer(new JsonByteArraySerializer());
+      mapper.registerModule(module);
+
       return mapper;
    }
-   
+
    @Bean
    public JsonFactory jsonFactory() {
       return new JsonFactory();
@@ -133,7 +139,7 @@ public class QueryRestConfig extends WebMvcConfigurerAdapter {
       String[] responseFields =
             StringUtils.commaDelimitedListToStringArray(env.getProperty(QUERYREST_DEFAULT_RESPONSE_FIELDS));
       LOGGER.debug("Load '{}={}'", BEAN_NAME_DEFAULT_RESPONSE_FIELDS, Arrays.toString(responseFields));
-      
+
       // preserve order
       LinkedHashSet<QueryField> defaultResponseFields = new LinkedHashSet<>(responseFields.length);
       for (String field : responseFields) {
@@ -152,7 +158,7 @@ public class QueryRestConfig extends WebMvcConfigurerAdapter {
       String[] responseAggregations =
             StringUtils.commaDelimitedListToStringArray(env.getProperty(QUERYREST_DEFAULT_RESPONSE_AGGREGATIONS));
       LOGGER.debug("Load '{}={}'", BEAN_NAME_DEFAULT_RESPONSE_AGGREGATIONS, Arrays.toString(responseAggregations));
-      
+
       // preserve order
       LinkedHashSet<Aggregation> defaultResponseAggregations = new LinkedHashSet<>(responseAggregations.length);
       for (String aggregation : responseAggregations) {
@@ -166,7 +172,7 @@ public class QueryRestConfig extends WebMvcConfigurerAdapter {
 
       return defaultResponseAggregations;
    }
-   
+
    @Bean
    public Validator queryValidator() {
       return new QueryValidator();
diff --git a/src/main/java/ch/psi/daq/queryrest/response/JsonByteArraySerializer.java b/src/main/java/ch/psi/daq/queryrest/response/JsonByteArraySerializer.java
new file mode 100644
index 0000000..e01cea1
--- /dev/null
+++ b/src/main/java/ch/psi/daq/queryrest/response/JsonByteArraySerializer.java
@@ -0,0 +1,30 @@
+package ch.psi.daq.queryrest.response;
+
+import java.io.IOException;
+
+import com.fasterxml.jackson.core.JsonGenerationException;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.ser.std.StdSerializer;
+
+// see: http://stackoverflow.com/a/15037329
+public class JsonByteArraySerializer extends StdSerializer<byte[]> {
+   private static final long serialVersionUID = -5914688899857435263L;
+
+   public JsonByteArraySerializer() {
+      super(byte[].class, true);
+   }
+
+   @Override
+   public void serialize(byte[] bytes, JsonGenerator jgen, SerializerProvider provider) throws IOException,
+         JsonGenerationException {
+      jgen.writeStartArray();
+
+      for (byte b : bytes) {
+         // stackoverflow example used a mask -> ?
+         jgen.writeNumber(b);
+      }
+
+      jgen.writeEndArray();
+   }
+}
diff --git a/src/main/java/ch/psi/daq/queryrest/response/ResponseStreamWriter.java b/src/main/java/ch/psi/daq/queryrest/response/ResponseStreamWriter.java
index 973ea78..e5c5483 100644
--- a/src/main/java/ch/psi/daq/queryrest/response/ResponseStreamWriter.java
+++ b/src/main/java/ch/psi/daq/queryrest/response/ResponseStreamWriter.java
@@ -12,6 +12,7 @@ import javax.servlet.ServletResponse;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.http.MediaType;
 
 import com.fasterxml.jackson.core.JsonEncoding;
 import com.fasterxml.jackson.core.JsonFactory;
@@ -100,6 +101,8 @@ public class ResponseStreamWriter {
          ObjectWriter writer)
          throws IOException {
 
+      response.setCharacterEncoding(JsonEncoding.UTF8.getJavaName());
+      response.setContentType(MediaType.APPLICATION_JSON_VALUE);
       JsonGenerator generator = jsonFactory.createGenerator(response.getOutputStream(), JsonEncoding.UTF8);
       generator.writeStartArray();
       stream
diff --git a/src/main/resources/queryrest.properties b/src/main/resources/queryrest.properties
index 1050546..762a6d3 100644
--- a/src/main/resources/queryrest.properties
+++ b/src/main/resources/queryrest.properties
@@ -3,5 +3,5 @@ server.port=8080
 
 # defines the fields that are included in the response 
 # if no fields have been specified by the user
-queryrest.default.response.fields=channel,pulseId,globalMillis,globalNanos,value
+queryrest.default.response.fields=channel,pulseId,globalMillis,globalNanos,iocMillis,iocNanos,value
 queryrest.default.response.aggregations=min,max,sum
\ No newline at end of file