diff --git a/core/src/main/kotlin/net/corda/core/internal/cordapp/CordappImpl.kt b/core/src/main/kotlin/net/corda/core/internal/cordapp/CordappImpl.kt
index 721d06bc15..366daabedc 100644
--- a/core/src/main/kotlin/net/corda/core/internal/cordapp/CordappImpl.kt
+++ b/core/src/main/kotlin/net/corda/core/internal/cordapp/CordappImpl.kt
@@ -34,14 +34,15 @@ data class CordappImpl(
         override val targetPlatformVersion: Int,
         val notaryService: Class<out NotaryService>? = null,
         /** Indicates whether the CorDapp is loaded from external sources, or generated on node startup (virtual). */
-        val isLoaded: Boolean = true
+        val isLoaded: Boolean = true,
+        private val explicitCordappClasses: List<String> = emptyList()
 ) : Cordapp {
     override val name: String = jarName(jarPath)
 
     // TODO: Also add [SchedulableFlow] as a Cordapp class
     override val cordappClasses: List<String> = run {
         val classList = rpcFlows + initiatedFlows + services + serializationWhitelists.map { javaClass } + notaryService
-        classList.mapNotNull { it?.name } + contractClassNames
+        classList.mapNotNull { it?.name } + contractClassNames + explicitCordappClasses
     }
 
     companion object {
diff --git a/core/src/main/kotlin/net/corda/core/internal/cordapp/CordappResolver.kt b/core/src/main/kotlin/net/corda/core/internal/cordapp/CordappResolver.kt
index 250ecb3e39..ff7fe11207 100644
--- a/core/src/main/kotlin/net/corda/core/internal/cordapp/CordappResolver.kt
+++ b/core/src/main/kotlin/net/corda/core/internal/cordapp/CordappResolver.kt
@@ -55,10 +55,10 @@ object CordappResolver {
     val currentCordapp: Cordapp? get() = cordappResolver()
 
     /**
-     * Returns the target version of the current calling CorDapp. Defaults to the current platform version if there isn't one.
+     * Returns the target version of the current calling CorDapp. Defaults to platform version 1 if there isn't one,
+     * assuming only basic platform capabilities.
      */
-    // TODO It may be the default is wrong and this should be Int? instead
-    val currentTargetVersion: Int get() = currentCordapp?.targetPlatformVersion ?: PLATFORM_VERSION
+    val currentTargetVersion: Int get() = currentCordapp?.targetPlatformVersion ?: 1
 
     /**
      * Temporarily apply a fake CorDapp with the given parameters. For use in testing.
diff --git a/core/src/test/kotlin/net/corda/core/transactions/TransactionBuilderTest.kt b/core/src/test/kotlin/net/corda/core/transactions/TransactionBuilderTest.kt
index d4d181a388..4881ebf5e7 100644
--- a/core/src/test/kotlin/net/corda/core/transactions/TransactionBuilderTest.kt
+++ b/core/src/test/kotlin/net/corda/core/transactions/TransactionBuilderTest.kt
@@ -11,6 +11,7 @@ import net.corda.core.identity.Party
 import net.corda.core.internal.AbstractAttachment
 import net.corda.core.internal.PLATFORM_VERSION
 import net.corda.core.internal.cordapp.CordappImpl.Companion.DEFAULT_CORDAPP_VERSION
+import net.corda.core.internal.cordapp.CordappResolver
 import net.corda.core.node.ServicesForResolution
 import net.corda.core.node.ZoneVersionTooLowException
 import net.corda.core.node.services.AttachmentStorage
@@ -116,20 +117,22 @@ class TransactionBuilderTest {
 
     @Test
     fun `multiple commands with same data are joined without duplicates in terms of signers`() {
-        val aliceParty = TestIdentity(ALICE_NAME).party
-        val bobParty = TestIdentity(BOB_NAME).party
-        val tx = TransactionBuilder(notary)
-        tx.addCommand(DummyCommandData, notary.owningKey, aliceParty.owningKey)
-        tx.addCommand(DummyCommandData, aliceParty.owningKey, bobParty.owningKey)
+        // This behaviour is only activated for platform version 4 onwards.
+        CordappResolver.withCordapp(targetPlatformVersion = 4) {
+            val aliceParty = TestIdentity(ALICE_NAME).party
+            val bobParty = TestIdentity(BOB_NAME).party
+            val tx = TransactionBuilder(notary)
+            tx.addCommand(DummyCommandData, notary.owningKey, aliceParty.owningKey)
+            tx.addCommand(DummyCommandData, aliceParty.owningKey, bobParty.owningKey)
 
-        val commands = tx.commands()
+            val commands = tx.commands()
 
-        assertThat(commands).hasSize(1)
-        assertThat(commands.single()).satisfies { cmd ->
-
-            assertThat(cmd.value).isEqualTo(DummyCommandData)
-            assertThat(cmd.signers).hasSize(3)
-            assertThat(cmd.signers).contains(notary.owningKey, bobParty.owningKey, aliceParty.owningKey)
+            assertThat(commands).hasSize(1)
+            assertThat(commands.single()).satisfies { cmd ->
+                assertThat(cmd.value).isEqualTo(DummyCommandData)
+                assertThat(cmd.signers).hasSize(3)
+                assertThat(cmd.signers).contains(notary.owningKey, bobParty.owningKey, aliceParty.owningKey)
+            }
         }
     }
 
diff --git a/node/src/main/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoader.kt b/node/src/main/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoader.kt
index 5518e985f1..4ffc90959b 100644
--- a/node/src/main/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoader.kt
+++ b/node/src/main/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoader.kt
@@ -151,7 +151,8 @@ class JarScanningCordappLoader private constructor(private val cordappJarPaths:
                 getJarHash(url.url),
                 minPlatformVersion,
                 targetPlatformVersion,
-                findNotaryService(this)
+                findNotaryService(this),
+                explicitCordappClasses = findAllCordappClasses(this)
         )
     }
 
@@ -250,6 +251,10 @@ class JarScanningCordappLoader private constructor(private val cordappJarPaths:
         return scanResult.getConcreteClassesOfType(FlowLogic::class)
     }
 
+    private fun findAllCordappClasses(scanResult: RestrictedScanResult): List<String> {
+        return scanResult.getAllStandardClasses() + scanResult.getAllInterfaces()
+    }
+
     private fun findContractClassNames(scanResult: RestrictedScanResult): List<String> {
         val contractClasses = coreContractClasses.flatMap { scanResult.getNamesOfClassesImplementing(it) }.distinct()
         for (contractClass in contractClasses) {
@@ -350,6 +355,20 @@ class JarScanningCordappLoader private constructor(private val cordappJarPaths:
                     .filterNot { it.isAbstractClass }
         }
 
+        fun getAllStandardClasses(): List<String> {
+            return scanResult
+                    .getAllStandardClasses()
+                    .names
+                    .filter { it.startsWith(qualifiedNamePrefix) }
+        }
+
+        fun getAllInterfaces(): List<String> {
+            return scanResult
+                    .getAllInterfaces()
+                    .names
+                    .filter { it.startsWith(qualifiedNamePrefix) }
+        }
+
         override fun close() = scanResult.close()
     }
 }