diff --git a/pom.xml b/pom.xml
index 8e79d7e..1b16dd4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,12 +5,12 @@
 
   <groupId>com.wikia</groupId>
   <artifactId>dropwizard-logstash-encoder</artifactId>
-  <version>1.0.2</version>
+  <version>1.0.3</version>
   <name>dropwizard-logstash-encoder</name>
   <description>
     Addon for dropwizard to log using the logback-logstash-encoder (see https://github.com/logstash/logstash-logback-encoder)
   </description>
-  <url>https://github.com/Wikia/dropwizard-logback-logsash-encoder</url>
+  <url>https://github.com/Wikia/dropwizard-logback-logstash-encoder</url>
 
   <licenses>
     <license>
@@ -128,12 +128,12 @@
     <dependency>
       <groupId>io.dropwizard</groupId>
       <artifactId>dropwizard-logging</artifactId>
-      <version>0.7.0</version>
+      <version>0.7.1</version>
     </dependency>
     <dependency>
       <groupId>net.logstash.logback</groupId>
       <artifactId>logstash-logback-encoder</artifactId>
-      <version>3.5</version>
+      <version>4.2</version>
     </dependency>
   </dependencies>
 </project>
diff --git a/src/main/java/com/wikia/dropwizard/logstash/appender/AbstractLogstashAppenderFactory.java b/src/main/java/com/wikia/dropwizard/logstash/appender/AbstractLogstashAppenderFactory.java
index 4cd0ef7..c164604 100644
--- a/src/main/java/com/wikia/dropwizard/logstash/appender/AbstractLogstashAppenderFactory.java
+++ b/src/main/java/com/wikia/dropwizard/logstash/appender/AbstractLogstashAppenderFactory.java
@@ -1,11 +1,13 @@
 package com.wikia.dropwizard.logstash.appender;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.collect.Maps;
 import io.dropwizard.logging.AbstractAppenderFactory;
 
 import javax.validation.constraints.Max;
 import javax.validation.constraints.Min;
 import javax.validation.constraints.NotNull;
+import java.io.IOException;
 import java.util.HashMap;
 
 abstract class AbstractLogstashAppenderFactory extends AbstractAppenderFactory {
@@ -22,7 +24,7 @@ abstract class AbstractLogstashAppenderFactory extends AbstractAppenderFactory {
 
   protected boolean includeMdc = true;
 
-  protected HashMap<String, String> customFields;
+  protected HashMap<String, String> customFields = Maps.newHashMap();
 
   protected HashMap<String, String> fieldNames;
 
@@ -95,4 +97,16 @@ public HashMap<String, String> getFieldNames() {
   public void setFieldNames(HashMap<String, String> fieldNames) {
     this.fieldNames = fieldNames;
   }
+
+  protected String renderCustomFields(String applicationName) {
+      // always set the application name except when overridden
+      customFields.putIfAbsent("applicationName", applicationName);
+
+      try {
+          return LogstashAppenderFactoryHelper.getCustomFieldsFromHashMap(customFields);
+      } catch (IOException e) {
+          System.out.println("unable to parse customFields: " + e.getMessage());
+          return "{}";
+      }
+    }
 }
diff --git a/src/main/java/com/wikia/dropwizard/logstash/appender/LogstashSocketAppenderFactory.java b/src/main/java/com/wikia/dropwizard/logstash/appender/LogstashSocketAppenderFactory.java
index d60d886..1c9b92e 100644
--- a/src/main/java/com/wikia/dropwizard/logstash/appender/LogstashSocketAppenderFactory.java
+++ b/src/main/java/com/wikia/dropwizard/logstash/appender/LogstashSocketAppenderFactory.java
@@ -8,8 +8,6 @@
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import net.logstash.logback.appender.LogstashSocketAppender;
 
-import java.io.IOException;
-
 @JsonTypeName("logstash-socket")
 public class LogstashSocketAppenderFactory extends AbstractLogstashAppenderFactory {
   public LogstashSocketAppenderFactory() {
@@ -29,14 +27,7 @@ public Appender<ILoggingEvent> build(LoggerContext context, String applicationNa
     appender.setIncludeMdc(includeMdc);
     appender.setIncludeContext(includeContext);
 
-    if (customFields != null) {
-      try {
-        String custom = LogstashAppenderFactoryHelper.getCustomFieldsFromHashMap(customFields);
-        appender.setCustomFields(custom);
-      } catch (IOException e) {
-        System.out.println("unable to parse customFields: "+e.getMessage());
-      }
-    }
+    appender.setCustomFields(renderCustomFields(applicationName));
 
     if (fieldNames != null) {
       appender.setFieldNames(LogstashAppenderFactoryHelper.getFieldNamesFromHashMap(fieldNames));
diff --git a/src/main/java/com/wikia/dropwizard/logstash/appender/LogstashTcpAppenderFactory.java b/src/main/java/com/wikia/dropwizard/logstash/appender/LogstashTcpAppenderFactory.java
index e34ec28..142c68a 100644
--- a/src/main/java/com/wikia/dropwizard/logstash/appender/LogstashTcpAppenderFactory.java
+++ b/src/main/java/com/wikia/dropwizard/logstash/appender/LogstashTcpAppenderFactory.java
@@ -11,7 +11,6 @@
 
 import javax.validation.constraints.Max;
 import javax.validation.constraints.Min;
-import java.io.IOException;
 
 @JsonTypeName("logstash-tcp")
 public class LogstashTcpAppenderFactory extends AbstractLogstashAppenderFactory {
@@ -59,14 +58,8 @@ public Appender<ILoggingEvent> build(LoggerContext context, String applicationNa
     encoder.setIncludeContext(includeContext);
     encoder.setIncludeMdc(includeMdc);
     encoder.setIncludeCallerInfo(includeCallerInfo);
-    if (customFields != null) {
-      try {
-        String custom = LogstashAppenderFactoryHelper.getCustomFieldsFromHashMap(customFields);
-        encoder.setCustomFields(custom);
-      } catch (IOException e) {
-        System.out.println("unable to parse customFields: "+e.getMessage());
-      }
-    }
+
+    encoder.setCustomFields(renderCustomFields(applicationName));
 
     if (fieldNames != null) {
       encoder.setFieldNames(LogstashAppenderFactoryHelper.getFieldNamesFromHashMap(fieldNames));
@@ -79,4 +72,5 @@ public Appender<ILoggingEvent> build(LoggerContext context, String applicationNa
 
     return wrapAsync(appender);
   }
+
 }