diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/EthType.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/EthType.java
index c5f4f86..1d9c8d6 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/EthType.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/EthType.java
@@ -218,7 +218,7 @@
 
     @Override
     public String toString() {
-        return Integer.toHexString(rawValue);
+        return "0x" + Integer.toHexString(rawValue);
     }
 
     public void write2Bytes(ChannelBuffer c) {
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv6FlowLabel.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv6FlowLabel.java
index de49b51..cfefd39 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv6FlowLabel.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv6FlowLabel.java
@@ -53,7 +53,7 @@
 
     @Override
     public String toString() {
-        return Integer.toHexString(label);
+        return "0x" + Integer.toHexString(label);
     }
 
     public void write4Bytes(ChannelBuffer c) {
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IpDscp.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IpDscp.java
index 27596b7..f19e051 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IpDscp.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IpDscp.java
@@ -227,7 +227,7 @@
 
     @Override
     public String toString() {
-        return Integer.toHexString(dscp);
+        return "0x" + Integer.toHexString(dscp);
     }
 
     public void writeByte(ChannelBuffer c) {
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IpProtocol.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IpProtocol.java
index 69f497e..8443a31 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IpProtocol.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IpProtocol.java
@@ -612,7 +612,7 @@
 
     @Override
     public String toString() {
-        return Integer.toHexString(proto);
+        return "0x" + Integer.toHexString(proto);
     }
 
     public void writeByte(ChannelBuffer c) {
@@ -662,4 +662,4 @@
         sink.putShort(proto);
     }
 
-}
\ No newline at end of file
+}