diff --git a/client/rpc/src/main/kotlin/net/corda/client/rpc/internal/serialization/amqp/AMQPClientSerializationScheme.kt b/client/rpc/src/main/kotlin/net/corda/client/rpc/internal/serialization/amqp/AMQPClientSerializationScheme.kt
index 6e094e87ee..473443bc9a 100644
--- a/client/rpc/src/main/kotlin/net/corda/client/rpc/internal/serialization/amqp/AMQPClientSerializationScheme.kt
+++ b/client/rpc/src/main/kotlin/net/corda/client/rpc/internal/serialization/amqp/AMQPClientSerializationScheme.kt
@@ -1,6 +1,7 @@
 package net.corda.client.rpc.internal.serialization.amqp
 
 import net.corda.core.cordapp.Cordapp
+import net.corda.core.internal.toSynchronised
 import net.corda.core.serialization.ClassWhitelist
 import net.corda.core.serialization.SerializationContext
 import net.corda.core.serialization.SerializationContext.UseCase
@@ -19,19 +20,19 @@ class AMQPClientSerializationScheme(
         cordappCustomSerializers: Set<SerializationCustomSerializer<*,*>>,
         serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>
     ) : AbstractAMQPSerializationScheme(cordappCustomSerializers, serializerFactoriesForContexts) {
-    constructor(cordapps: List<Cordapp>) : this(cordapps.customSerializers, AccessOrderLinkedHashMap { 128 })
+    constructor(cordapps: List<Cordapp>) : this(cordapps.customSerializers, AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>(128).toSynchronised())
     constructor(cordapps: List<Cordapp>, serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>) : this(cordapps.customSerializers, serializerFactoriesForContexts)
 
     @Suppress("UNUSED")
-    constructor() : this(emptySet(), AccessOrderLinkedHashMap { 128 })
+    constructor() : this(emptySet(), AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>(128).toSynchronised())
 
     companion object {
         /** Call from main only. */
-        fun initialiseSerialization(classLoader: ClassLoader? = null, serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory> = AccessOrderLinkedHashMap { 128 }) {
+        fun initialiseSerialization(classLoader: ClassLoader? = null, serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory> = AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>(128).toSynchronised()) {
             nodeSerializationEnv = createSerializationEnv(classLoader, serializerFactoriesForContexts)
         }
 
-        fun createSerializationEnv(classLoader: ClassLoader? = null, serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory> = AccessOrderLinkedHashMap { 128 }): SerializationEnvironment {
+        fun createSerializationEnv(classLoader: ClassLoader? = null, serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory> = AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>(128).toSynchronised()): SerializationEnvironment {
             return SerializationEnvironment.with(
                     SerializationFactoryImpl().apply {
                         registerScheme(AMQPClientSerializationScheme(emptyList(), serializerFactoriesForContexts))
diff --git a/node/src/main/kotlin/net/corda/node/serialization/amqp/AMQPServerSerializationScheme.kt b/node/src/main/kotlin/net/corda/node/serialization/amqp/AMQPServerSerializationScheme.kt
index 1cb164b0eb..e1cc44d805 100644
--- a/node/src/main/kotlin/net/corda/node/serialization/amqp/AMQPServerSerializationScheme.kt
+++ b/node/src/main/kotlin/net/corda/node/serialization/amqp/AMQPServerSerializationScheme.kt
@@ -1,6 +1,7 @@
 package net.corda.node.serialization.amqp
 
 import net.corda.core.cordapp.Cordapp
+import net.corda.core.internal.toSynchronised
 import net.corda.core.serialization.ClassWhitelist
 import net.corda.core.serialization.SerializationContext
 import net.corda.core.serialization.SerializationCustomSerializer
@@ -19,10 +20,10 @@ class AMQPServerSerializationScheme(
         cordappCustomSerializers: Set<SerializationCustomSerializer<*, *>>,
         serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>
 ) : AbstractAMQPSerializationScheme(cordappCustomSerializers, serializerFactoriesForContexts) {
-    constructor(cordapps: List<Cordapp>) : this(cordapps.customSerializers, AccessOrderLinkedHashMap { 128 })
+    constructor(cordapps: List<Cordapp>) : this(cordapps.customSerializers, AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>(128).toSynchronised())
     constructor(cordapps: List<Cordapp>, serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>) : this(cordapps.customSerializers, serializerFactoriesForContexts)
 
-    constructor() : this(emptySet(), AccessOrderLinkedHashMap { 128 })
+    constructor() : this(emptySet(), AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>(128).toSynchronised() )
 
     override fun rpcClientSerializerFactory(context: SerializationContext): SerializerFactory {
         throw UnsupportedOperationException()
diff --git a/node/src/test/kotlin/net/corda/node/internal/serialization/RoundTripObservableSerializerTests.kt b/node/src/test/kotlin/net/corda/node/internal/serialization/RoundTripObservableSerializerTests.kt
index 9a0a8d042c..4e7729d20e 100644
--- a/node/src/test/kotlin/net/corda/node/internal/serialization/RoundTripObservableSerializerTests.kt
+++ b/node/src/test/kotlin/net/corda/node/internal/serialization/RoundTripObservableSerializerTests.kt
@@ -8,6 +8,8 @@ import com.nhaarman.mockito_kotlin.mock
 import net.corda.client.rpc.internal.serialization.amqp.RpcClientObservableDeSerializer
 import net.corda.core.context.Trace
 import net.corda.core.internal.ThreadBox
+import net.corda.core.internal.toSynchronised
+import net.corda.core.serialization.ClassWhitelist
 import net.corda.node.internal.serialization.testutils.AMQPRoundTripRPCSerializationScheme
 import net.corda.node.internal.serialization.testutils.serializationContext
 import net.corda.node.serialization.amqp.RpcServerObservableSerializer
@@ -16,6 +18,7 @@ import net.corda.nodeapi.RPCApi
 import net.corda.serialization.internal.amqp.AccessOrderLinkedHashMap
 import net.corda.serialization.internal.amqp.DeserializationInput
 import net.corda.serialization.internal.amqp.SerializationOutput
+import net.corda.serialization.internal.amqp.SerializerFactory
 import org.apache.activemq.artemis.api.core.SimpleString
 import org.junit.Test
 import rx.Notification
@@ -60,7 +63,7 @@ class RoundTripObservableSerializerTests {
     @Test
     fun roundTripTest1() {
         val serializationScheme = AMQPRoundTripRPCSerializationScheme(
-                serializationContext, emptySet(), AccessOrderLinkedHashMap { 128 })
+                serializationContext, emptySet(), AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>(128).toSynchronised())
 
         // Fake up a message ID, needs to be used on both "sides". The server setting it in the subscriptionMap,
         // the client as a property of the deserializer which, in the actual RPC client, is pulled off of
diff --git a/node/src/test/kotlin/net/corda/node/internal/serialization/testutils/AMQPTestSerialiationScheme.kt b/node/src/test/kotlin/net/corda/node/internal/serialization/testutils/AMQPTestSerialiationScheme.kt
index 7a803cb661..86629bcbed 100644
--- a/node/src/test/kotlin/net/corda/node/internal/serialization/testutils/AMQPTestSerialiationScheme.kt
+++ b/node/src/test/kotlin/net/corda/node/internal/serialization/testutils/AMQPTestSerialiationScheme.kt
@@ -24,7 +24,7 @@ import net.corda.client.rpc.internal.ObservableContext as ClientObservableContex
 class AMQPRoundTripRPCSerializationScheme(
         private val serializationContext: SerializationContext,
         cordappCustomSerializers: Set<SerializationCustomSerializer<*, *>>,
-        serializerFactoriesForContexts: AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>)
+        serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>)
     : AbstractAMQPSerializationScheme(
         cordappCustomSerializers, serializerFactoriesForContexts
 ) {
diff --git a/serialization/src/main/kotlin/net/corda/serialization/internal/amqp/AMQPSerializationScheme.kt b/serialization/src/main/kotlin/net/corda/serialization/internal/amqp/AMQPSerializationScheme.kt
index b9feeccc0a..7cbe22b116 100644
--- a/serialization/src/main/kotlin/net/corda/serialization/internal/amqp/AMQPSerializationScheme.kt
+++ b/serialization/src/main/kotlin/net/corda/serialization/internal/amqp/AMQPSerializationScheme.kt
@@ -9,6 +9,7 @@ import net.corda.core.StubOutForDJVM
 import net.corda.core.cordapp.Cordapp
 import net.corda.core.internal.isAbstractClass
 import net.corda.core.internal.objectOrNewInstance
+import net.corda.core.internal.toSynchronised
 import net.corda.core.internal.uncheckedCast
 import net.corda.core.serialization.*
 import net.corda.core.utilities.ByteSequence
@@ -44,7 +45,7 @@ abstract class AbstractAMQPSerializationScheme(
         val sff: SerializerFactoryFactory = createSerializerFactoryFactory()
 ) : SerializationScheme {
     @DeleteForDJVM
-    constructor(cordapps: List<Cordapp>) : this(cordapps.customSerializers, AccessOrderLinkedHashMap(128))
+    constructor(cordapps: List<Cordapp>) : this(cordapps.customSerializers, AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>(128).toSynchronised())
 
     // This is a bit gross but a broader check for ConcurrentMap is not allowed inside DJVM.
     private val serializerFactoriesForContexts: MutableMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory> = if (maybeNotConcurrentSerializerFactoriesForContexts is AccessOrderLinkedHashMap<*, *>) {
diff --git a/serialization/src/test/kotlin/net/corda/serialization/internal/amqp/AbstractAMQPSerializationSchemeTest.kt b/serialization/src/test/kotlin/net/corda/serialization/internal/amqp/AbstractAMQPSerializationSchemeTest.kt
index eaaeffb043..b8be1f9b3b 100644
--- a/serialization/src/test/kotlin/net/corda/serialization/internal/amqp/AbstractAMQPSerializationSchemeTest.kt
+++ b/serialization/src/test/kotlin/net/corda/serialization/internal/amqp/AbstractAMQPSerializationSchemeTest.kt
@@ -1,5 +1,6 @@
 package net.corda.serialization.internal.amqp
 
+import net.corda.core.internal.toSynchronised
 import net.corda.core.serialization.ClassWhitelist
 import net.corda.core.serialization.SerializationContext
 import net.corda.core.serialization.deserialize
@@ -39,7 +40,7 @@ class AbstractAMQPSerializationSchemeTest {
 
         val factory = SerializerFactoryBuilder.build(TESTING_CONTEXT.whitelist, TESTING_CONTEXT.deserializationClassLoader)
         val maxFactories = 512
-        val backingMap = AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>({ maxFactories })
+        val backingMap = AccessOrderLinkedHashMap<Pair<ClassWhitelist, ClassLoader>, SerializerFactory>({ maxFactories }).toSynchronised()
         val scheme = object : AbstractAMQPSerializationScheme(emptySet(), backingMap, createSerializerFactoryFactory()) {
             override fun rpcClientSerializerFactory(context: SerializationContext): SerializerFactory {
                 return factory