diff --git a/android/src/main/kotlin/de/mintware/barcode_scan/ActivityHelper.kt b/android/src/main/kotlin/de/mintware/barcode_scan/ActivityHelper.kt
index 48adf82..bac5b00 100644
--- a/android/src/main/kotlin/de/mintware/barcode_scan/ActivityHelper.kt
+++ b/android/src/main/kotlin/de/mintware/barcode_scan/ActivityHelper.kt
@@ -69,8 +69,8 @@ class ActivityHelper(private var applicationContext: Context?,
     }
 
     override fun onRequestPermissionsResult(requestCode: Int,
-                                            permissions: Array<out String>?,
-                                            grantResults: IntArray?
+                                            permissions: Array<out String>,
+                                            grantResults: IntArray
     ): Boolean {
         if (!permissionResultMap.containsKey(requestCode)) {
             return false
diff --git a/android/src/main/kotlin/de/mintware/barcode_scan/ChannelHandler.kt b/android/src/main/kotlin/de/mintware/barcode_scan/ChannelHandler.kt
index c7d4661..a1c0608 100644
--- a/android/src/main/kotlin/de/mintware/barcode_scan/ChannelHandler.kt
+++ b/android/src/main/kotlin/de/mintware/barcode_scan/ChannelHandler.kt
@@ -56,7 +56,7 @@ class ChannelHandler(private val activityHelper: ActivityHelper
         result.success(activityHelper.requestCameraAccessIfNecessary(sink))
     }
 
-    fun startListening(messenger: BinaryMessenger?) {
+    fun startListening(messenger: BinaryMessenger) {
         if (methodChannel != null) {
             stopListening()
         }
diff --git a/android/src/main/kotlin/de/mintware/barcode_scan/RequestCameraPermissionHandler.kt b/android/src/main/kotlin/de/mintware/barcode_scan/RequestCameraPermissionHandler.kt
index 53691c7..997df6d 100644
--- a/android/src/main/kotlin/de/mintware/barcode_scan/RequestCameraPermissionHandler.kt
+++ b/android/src/main/kotlin/de/mintware/barcode_scan/RequestCameraPermissionHandler.kt
@@ -9,8 +9,8 @@ class RequestCameraPermissionHandler(private val sink: EventChannel.EventSink?
 ) : PluginRegistry.RequestPermissionsResultListener {
 
     override fun onRequestPermissionsResult(requestCode: Int,
-                                            permissions: Array<out String>?,
-                                            grantResults: IntArray?
+                                            permissions: Array<out String>,
+                                            grantResults: IntArray
     ): Boolean {
         if (requestCode != REQ_CAMERA_PERMISSION) {
             return false
@@ -30,7 +30,7 @@ class RequestCameraPermissionHandler(private val sink: EventChannel.EventSink?
 
      * @see onRequestPermissionsResult
      */
-    private fun verifyPermissions(grantResults: IntArray?): Boolean {
+    private fun verifyPermissions(grantResults: IntArray): Boolean {
         if (grantResults == null) {
             return false
         }