diff --git a/src/main/kotlin/com/beust/kobalt/plugin/kotlin/KotlinCompiler.kt b/src/main/kotlin/com/beust/kobalt/plugin/kotlin/KotlinCompiler.kt
index 0bbca05f..165c92c9 100644
--- a/src/main/kotlin/com/beust/kobalt/plugin/kotlin/KotlinCompiler.kt
+++ b/src/main/kotlin/com/beust/kobalt/plugin/kotlin/KotlinCompiler.kt
@@ -161,7 +161,7 @@ class KotlinCompiler @Inject constructor(
 }
 
 class KConfiguration @Inject constructor(val compiler: KotlinCompiler){
-    val classpath = arrayListOf<String>()
+    private val classpath = arrayListOf<String>()
     val dependencies = arrayListOf<IClasspathDependency>()
     var source = arrayListOf<String>()
     var output: File by Delegates.notNull()