diff --git a/build.gradle b/build.gradle
index a10d7ba6c1..bf5254cc47 100644
--- a/build.gradle
+++ b/build.gradle
@@ -25,7 +25,7 @@ allprojects {
         }
     }
 
-    configurations{
+    configurations {
         // This is for the latest deterministic Corda SNAPSHOT artifacts...
         [ compileClasspath, runtimeClasspath ].forEach { cfg ->
             cfg.resolutionStrategy {
@@ -38,6 +38,11 @@ allprojects {
                 }
             }
         }
+
+        testRuntimeClasspath.resolutionStrategy {
+            // Always check the repository for a newer SNAPSHOT.
+            cacheChangingModulesFor 0, 'seconds'
+        }
     }
 
     /*
diff --git a/src/main/kotlin/net/corda/djvm/serialization/SandboxSerializerFactoryFactory.kt b/src/main/kotlin/net/corda/djvm/serialization/SandboxSerializerFactoryFactory.kt
index d6afa000fd..9b15bcfe6b 100644
--- a/src/main/kotlin/net/corda/djvm/serialization/SandboxSerializerFactoryFactory.kt
+++ b/src/main/kotlin/net/corda/djvm/serialization/SandboxSerializerFactoryFactory.kt
@@ -14,6 +14,7 @@ import java.util.*
 import java.util.Collections.singleton
 import java.util.Collections.unmodifiableMap
 import java.util.function.Function
+import java.util.function.Predicate
 
 /**
  * This has all been lovingly copied from [SerializerFactoryBuilder].
@@ -60,6 +61,7 @@ class SandboxSerializerFactoryFactory(
             classloader = classLoader,
             descriptorBasedSerializerRegistry = descriptorBasedSerializerRegistry,
             primitiveSerializerFactory = primitiveSerializerFactory,
+            isPrimitiveType = Predicate { clazz -> clazz.isPrimitive || clazz in primitiveTypes.keys },
             customSerializerRegistry = customSerializerRegistry,
             onlyCustomSerializers = false
         )