diff --git a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt
index b52bdce5cd9..2a5727685b5 100644
--- a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt
+++ b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt
@@ -36,7 +36,7 @@ public open class KotlinCompile(): AbstractCompile() {
     override fun setSource(source: Any?) {
         srcDirsRoots.clear()
         if (source is SourceDirectorySet) {
-            srcDirsRoots.addAll(source.getSrcDirs())
+            srcDirsRoots.addAll(source.getSrcDirs()!!)
         }
         super.setSource(source)
     }
@@ -45,7 +45,7 @@ public open class KotlinCompile(): AbstractCompile() {
     override fun source(vararg sources: Any?): SourceTask? {
         for (source in sources) {
             if (source is SourceDirectorySet) {
-                srcDirsRoots.addAll(source.getSrcDirs())
+                srcDirsRoots.addAll(source.getSrcDirs()!!)
             }
         }
         return super.source(sources)