diff --git a/tools/checkpoint-agent/build.gradle b/tools/checkpoint-agent/build.gradle
index 442f63eea8..d32317db49 100644
--- a/tools/checkpoint-agent/build.gradle
+++ b/tools/checkpoint-agent/build.gradle
@@ -6,7 +6,7 @@ description 'A javaagent to allow hooking into Kryo checkpoints'
 
 dependencies {
     compileOnly "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
-    compileOnly "org.javassist:javassist:$javaassist_version"
+    implementation "org.javassist:javassist:$javaassist_version"
     compileOnly "com.esotericsoftware:kryo:$kryo_version"
     compileOnly "co.paralleluniverse:quasar-core:$quasar_version"
 
diff --git a/tools/checkpoint-agent/src/main/kotlin/net/corda/tools/CheckpointAgent.kt b/tools/checkpoint-agent/src/main/kotlin/net/corda/tools/CheckpointAgent.kt
index ce186dacc4..1207e1504c 100644
--- a/tools/checkpoint-agent/src/main/kotlin/net/corda/tools/CheckpointAgent.kt
+++ b/tools/checkpoint-agent/src/main/kotlin/net/corda/tools/CheckpointAgent.kt
@@ -127,7 +127,9 @@ object CheckpointHook : ClassFileTransformer {
             protectionDomain: ProtectionDomain?,
             classfileBuffer: ByteArray
     ): ByteArray? {
-        if (className.startsWith("java") || className.startsWith("javassist") || className.startsWith("kotlin")) {
+        @Suppress("ComplexCondition")
+        if (className.startsWith("java") || className.startsWith("javassist") || className.startsWith("kotlin")
+                || className.startsWith("jdk")) {
             return null
         }
         return try {