diff --git a/core/src/main/kotlin/com/r3corda/core/serialization/Kryo.kt b/core/src/main/kotlin/com/r3corda/core/serialization/Kryo.kt
index b825883de8..520b54588c 100644
--- a/core/src/main/kotlin/com/r3corda/core/serialization/Kryo.kt
+++ b/core/src/main/kotlin/com/r3corda/core/serialization/Kryo.kt
@@ -260,14 +260,16 @@ object WireTransactionSerializer : Serializer<WireTransaction>() {
 @ThreadSafe
 object Ed25519PrivateKeySerializer : Serializer<EdDSAPrivateKey>() {
     val ed25519Curve = EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.CURVE_ED25519_SHA512)
+    val seedSize = 64
 
     override fun write(kryo: Kryo, output: Output, obj: EdDSAPrivateKey) {
         check(obj.params.equals(ed25519Curve))
-        kryo.writeClassAndObject(output, obj.seed)
+        check(obj.seed.size == seedSize)
+        output.writeBytes(obj.seed)
     }
 
     override fun read(kryo: Kryo, input: Input, type: Class<EdDSAPrivateKey>): EdDSAPrivateKey {
-        val seed = kryo.readClassAndObject(input) as ByteArray
+        val seed = input.readBytes(seedSize)
         return EdDSAPrivateKey(EdDSAPrivateKeySpec(seed, ed25519Curve))
     }
 }
@@ -276,14 +278,16 @@ object Ed25519PrivateKeySerializer : Serializer<EdDSAPrivateKey>() {
 @ThreadSafe
 object Ed25519PublicKeySerializer : Serializer<EdDSAPublicKey>() {
     val ed25519Curve = EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.CURVE_ED25519_SHA512)
+    val ASize = 32
 
     override fun write(kryo: Kryo, output: Output, obj: EdDSAPublicKey) {
         check(obj.params.equals(ed25519Curve))
-        kryo.writeClassAndObject(output, obj.abyte)
+        check(obj.abyte.size == ASize)
+        output.writeBytes(obj.abyte)
     }
 
     override fun read(kryo: Kryo, input: Input, type: Class<EdDSAPublicKey>): EdDSAPublicKey {
-        val A = kryo.readClassAndObject(input) as ByteArray
+        val A = input.readBytes(ASize)
         return EdDSAPublicKey(EdDSAPublicKeySpec(A, ed25519Curve))
     }
 }