diff --git a/core/src/main/kotlin/net/corda/core/internal/InternalUtils.kt b/core/src/main/kotlin/net/corda/core/internal/InternalUtils.kt
index 0ef6a73f84..3b5c8752ea 100644
--- a/core/src/main/kotlin/net/corda/core/internal/InternalUtils.kt
+++ b/core/src/main/kotlin/net/corda/core/internal/InternalUtils.kt
@@ -1,7 +1,15 @@
 package net.corda.core.internal
 
+import net.corda.core.contracts.AttachmentResolutionException
+import net.corda.core.contracts.TransactionResolutionException
 import net.corda.core.crypto.SecureHash
 import net.corda.core.crypto.sha256
+import net.corda.core.node.ServiceHub
+import net.corda.core.node.ServicesForResolution
+import net.corda.core.serialization.SerializationContext
+import net.corda.core.transactions.MissingContractAttachments
+import net.corda.core.transactions.TransactionBuilder
+import net.corda.core.transactions.WireTransaction
 import org.bouncycastle.cert.X509CertificateHolder
 import org.bouncycastle.cert.jcajce.JcaX509CertificateConverter
 import org.slf4j.Logger
@@ -274,4 +282,12 @@ annotation class VisibleForTesting
 @Suppress("UNCHECKED_CAST")
 fun <T, U : T> uncheckedCast(obj: T) = obj as U
 
-fun <K, V> Iterable<Pair<K, V>>.toMultiMap(): Map<K, List<V>> = this.groupBy({ it.first }) { it.second }
\ No newline at end of file
+fun <K, V> Iterable<Pair<K, V>>.toMultiMap(): Map<K, List<V>> = this.groupBy({ it.first }) { it.second }
+
+// Provide access to internal method for AttachmentClassLoaderTests
+fun TransactionBuilder.toWireTransaction(services: ServicesForResolution, serializationContext: SerializationContext): WireTransaction {
+    return toWireTransactionWithContext(services, serializationContext)
+}
+
+// Provide access to internal method for AttachmentClassLoaderTests
+fun TransactionBuilder.toLedgerTransaction(services: ServiceHub, serializationContext: SerializationContext) = toLedgerTransactionWithContext(services, serializationContext)
diff --git a/core/src/main/kotlin/net/corda/core/transactions/TransactionBuilder.kt b/core/src/main/kotlin/net/corda/core/transactions/TransactionBuilder.kt
index 9f972ee155..ad6c538451 100644
--- a/core/src/main/kotlin/net/corda/core/transactions/TransactionBuilder.kt
+++ b/core/src/main/kotlin/net/corda/core/transactions/TransactionBuilder.kt
@@ -81,9 +81,10 @@ open class TransactionBuilder(
      *
      * @returns A new [WireTransaction] that will be unaffected by further changes to this [TransactionBuilder].
      */
-    @JvmOverloads
     @Throws(MissingContractAttachments::class)
-    fun toWireTransaction(services: ServicesForResolution, serializationContext: SerializationContext? = null): WireTransaction {
+    fun toWireTransaction(services: ServicesForResolution): WireTransaction = toWireTransactionWithContext(services)
+
+    internal fun toWireTransactionWithContext(services: ServicesForResolution, serializationContext: SerializationContext? = null): WireTransaction {
         // Resolves the AutomaticHashConstraints to HashAttachmentConstraints for convenience. The AutomaticHashConstraint
         // allows for less boiler plate when constructing transactions since for the typical case the named contract
         // will be available when building the transaction. In exceptional cases the TransactionStates must be created
@@ -103,7 +104,9 @@ open class TransactionBuilder(
     }
 
     @Throws(AttachmentResolutionException::class, TransactionResolutionException::class)
-    fun toLedgerTransaction(services: ServiceHub, serializationContext: SerializationContext? = null) = toWireTransaction(services, serializationContext).toLedgerTransaction(services)
+    fun toLedgerTransaction(services: ServiceHub) = toWireTransaction(services).toLedgerTransaction(services)
+
+    internal fun toLedgerTransactionWithContext(services: ServiceHub, serializationContext: SerializationContext) = toWireTransactionWithContext(services, serializationContext).toLedgerTransaction(services)
 
     @Throws(AttachmentResolutionException::class, TransactionResolutionException::class, TransactionVerificationException::class)
     fun verify(services: ServiceHub) {
diff --git a/node-api/src/test/kotlin/net/corda/nodeapi/internal/AttachmentsClassLoaderTests.kt b/node-api/src/test/kotlin/net/corda/nodeapi/internal/AttachmentsClassLoaderTests.kt
index 5fc205e666..9d756a8812 100644
--- a/node-api/src/test/kotlin/net/corda/nodeapi/internal/AttachmentsClassLoaderTests.kt
+++ b/node-api/src/test/kotlin/net/corda/nodeapi/internal/AttachmentsClassLoaderTests.kt
@@ -5,6 +5,8 @@ import com.nhaarman.mockito_kotlin.whenever
 import net.corda.core.contracts.*
 import net.corda.core.crypto.SecureHash
 import net.corda.core.internal.declaredField
+import net.corda.core.internal.toLedgerTransaction
+import net.corda.core.internal.toWireTransaction
 import net.corda.core.node.ServiceHub
 import net.corda.core.node.services.AttachmentStorage
 import net.corda.core.serialization.*
diff --git a/node/src/integration-test/kotlin/net/corda/node/services/AttachmentLoadingTests.kt b/node/src/integration-test/kotlin/net/corda/node/services/AttachmentLoadingTests.kt
index 03b9a9435e..7adf8de10e 100644
--- a/node/src/integration-test/kotlin/net/corda/node/services/AttachmentLoadingTests.kt
+++ b/node/src/integration-test/kotlin/net/corda/node/services/AttachmentLoadingTests.kt
@@ -9,6 +9,7 @@ import net.corda.core.identity.Party
 import net.corda.core.internal.concurrent.transpose
 import net.corda.core.internal.createDirectories
 import net.corda.core.internal.div
+import net.corda.core.internal.toLedgerTransaction
 import net.corda.core.serialization.SerializationFactory
 import net.corda.core.transactions.TransactionBuilder
 import net.corda.core.utilities.OpaqueBytes