diff --git a/core/java/src/net/i2p/data/Certificate.java b/core/java/src/net/i2p/data/Certificate.java
index aefc34ce61f1ae5ba836bfedae2eb142f979f359..200423d8bffcb18171e162796bc21d4bdcea5323 100644
--- a/core/java/src/net/i2p/data/Certificate.java
+++ b/core/java/src/net/i2p/data/Certificate.java
@@ -176,7 +176,7 @@ public class Certificate extends DataStructureImpl {
         if (_type < 0) throw new DataFormatException("Invalid certificate type: " + _type);
         //if ((_type != 0) && (_payload == null)) throw new DataFormatException("Payload is required for non null type");
 
-        DataHelper.writeLong(out, 1, _type);
+        out.write((byte) _type);
         if (_payload != null) {
             DataHelper.writeLong(out, 2, _payload.length);
             out.write(_payload);