diff --git a/src/main/kotlin/com/beust/kobalt/api/ICompilerFlagContributor.kt b/src/main/kotlin/com/beust/kobalt/api/ICompilerFlagContributor.kt
index 896ed3e2..87757868 100644
--- a/src/main/kotlin/com/beust/kobalt/api/ICompilerFlagContributor.kt
+++ b/src/main/kotlin/com/beust/kobalt/api/ICompilerFlagContributor.kt
@@ -4,5 +4,5 @@ package com.beust.kobalt.api
  * Plugins that add compiler flags.
  */
 interface ICompilerFlagContributor : IContributor {
-    fun flagsFor(project: Project): List<String>
+    fun flagsFor(project: Project, currentFlags: List<String>): List<String>
 }
diff --git a/src/main/kotlin/com/beust/kobalt/internal/JvmCompiler.kt b/src/main/kotlin/com/beust/kobalt/internal/JvmCompiler.kt
index a4d2bc36..5cdc804e 100644
--- a/src/main/kotlin/com/beust/kobalt/internal/JvmCompiler.kt
+++ b/src/main/kotlin/com/beust/kobalt/internal/JvmCompiler.kt
@@ -32,7 +32,7 @@ class JvmCompiler @Inject constructor(val dependencyManager: DependencyManager)
         val addedFlags = ArrayList(info.compilerArgs) +
             if (project != null) {
                 context.pluginInfo.compilerFlagContributors.flatMap {
-                    it.flagsFor(project)
+                    it.flagsFor(project, info.compilerArgs)
                 }
             } else {
                 emptyList()
diff --git a/src/main/kotlin/com/beust/kobalt/plugin/apt/AptPlugin.kt b/src/main/kotlin/com/beust/kobalt/plugin/apt/AptPlugin.kt
index 34a91534..d8b2566b 100644
--- a/src/main/kotlin/com/beust/kobalt/plugin/apt/AptPlugin.kt
+++ b/src/main/kotlin/com/beust/kobalt/plugin/apt/AptPlugin.kt
@@ -27,14 +27,14 @@ public class AptPlugin @Inject constructor(val depFactory: DepFactory, val execu
     override val name = NAME
 
     // ICompilerFlagContributor
-    override fun flagsFor(project: Project) : List<String> {
+    override fun flagsFor(project: Project, currentFlags: List<String>) : List<String> {
         val result = arrayListOf<String>()
         configurationFor(project)?.let { config ->
             aptDependencies.get(key = project.name)?.let { aptDependency ->
                 val dependencyJarFile = JarFinder.byId(aptDependency)
                 result.add("-processorpath")
                 result.add(dependencyJarFile.absolutePath)
-                val generated = KFiles.joinAndMakeDir(project.directory, project.buildDirectory!!, config.outputDir)
+                val generated = KFiles.joinAndMakeDir(project.directory, project.buildDirectory, config.outputDir)
                 result.add("-s")
                 result.add(generated)
             }