diff --git a/app/src/main/kotlin/com/tutpro/baresip/AccountActivity.kt b/app/src/main/kotlin/com/tutpro/baresip/AccountActivity.kt
index 73f344fe..95a25884 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/AccountActivity.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/AccountActivity.kt
@@ -34,7 +34,7 @@ class AccountActivity : AppCompatActivity() {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_account)
 
-        acc = Account.find(intent.extras.getString("accp"))!!
+        acc = Account.find(intent.getStringExtra("accp"))!!
         aor = acc.aor
         uaIndex = UserAgent.findAorIndex(aor)!!
 
diff --git a/app/src/main/kotlin/com/tutpro/baresip/AccountsActivity.kt b/app/src/main/kotlin/com/tutpro/baresip/AccountsActivity.kt
index 2eb44f3f..eeba7381 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/AccountsActivity.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/AccountsActivity.kt
@@ -62,7 +62,7 @@ class AccountsActivity : AppCompatActivity() {
             }
         }
 
-        val accp = intent.extras.getString("accp")
+        val accp = intent.getStringExtra("accp")
         if (accp != "") {
             val i = Intent(this, AccountActivity::class.java)
             val b = Bundle()
diff --git a/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt b/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
index 85cdd634..986fb4a9 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
@@ -667,7 +667,6 @@ class BaresipService: Service() {
     }
 
     private fun requestAudioFocus(streamType: Int) {
-        val res: Int
         if ((Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) && (audioFocusRequest == null)) {
             @TargetApi(26)
             audioFocusRequest = AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN).run {
@@ -678,16 +677,15 @@ class BaresipService: Service() {
                 build()
             }
             @TargetApi(26)
-            res = am.requestAudioFocus(audioFocusRequest)
-            if (res == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
+            if (am.requestAudioFocus(audioFocusRequest!!) == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
                 Log.d(LOG_TAG, "Audio focus granted")
             } else {
                 Log.d(LOG_TAG, "Audio focus denied")
                 audioFocusRequest = null
             }
         } else {
-            res = am.requestAudioFocus(null, streamType, AudioManager.AUDIOFOCUS_GAIN)
-            if (res == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
+            if (am.requestAudioFocus(null, streamType, AudioManager.AUDIOFOCUS_GAIN) ==
+                    AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
                 Log.d(LOG_TAG, "Audio focus granted")
                 audioFocused = true
             } else {
@@ -700,7 +698,7 @@ class BaresipService: Service() {
     private fun abandonAudioFocus() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             if (audioFocusRequest != null) {
-                am.abandonAudioFocusRequest(audioFocusRequest)
+                am.abandonAudioFocusRequest(audioFocusRequest!!)
                 audioFocusRequest = null
             }
         } else {
diff --git a/app/src/main/kotlin/com/tutpro/baresip/CallsActivity.kt b/app/src/main/kotlin/com/tutpro/baresip/CallsActivity.kt
index c20bd6e0..df943555 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/CallsActivity.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/CallsActivity.kt
@@ -26,7 +26,7 @@ class CallsActivity : AppCompatActivity() {
 
         setContentView(R.layout.activity_calls)
 
-        val aor = intent.extras.getString("aor")
+        val aor = intent.getStringExtra("aor")!!
         val ua = Account.findUa(aor)!!
 
         val headerView = findViewById(R.id.account) as TextView
@@ -71,7 +71,7 @@ class CallsActivity : AppCompatActivity() {
         }
         listView.onItemLongClickListener = AdapterView.OnItemLongClickListener { _, _, pos, _ ->
             val peerUri = uaHistory[pos].peerURI
-            var peerName = ContactsActivity.contactName(peerUri)
+            val peerName = ContactsActivity.contactName(peerUri)
             val dialogClickListener = DialogInterface.OnClickListener { _, which ->
                 when (which) {
                     DialogInterface.BUTTON_NEUTRAL -> {
diff --git a/app/src/main/kotlin/com/tutpro/baresip/ChatActivity.kt b/app/src/main/kotlin/com/tutpro/baresip/ChatActivity.kt
index 458d5baa..a6924b93 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/ChatActivity.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/ChatActivity.kt
@@ -35,9 +35,9 @@ class ChatActivity : AppCompatActivity() {
 
         setContentView(R.layout.activity_chat)
 
-        aor = intent.extras.getString("aor")
-        peerUri = intent.extras.getString("peer")
-        val focus = intent.extras.getBoolean("focus")
+        aor = intent.getStringExtra("aor")!!
+        peerUri = intent.getStringExtra("peer")!!
+        val focus = intent.getBooleanExtra("focus", false)
 
         val userAgent = Account.findUa(aor)
         if (userAgent == null) {
diff --git a/app/src/main/kotlin/com/tutpro/baresip/ChatsActivity.kt b/app/src/main/kotlin/com/tutpro/baresip/ChatsActivity.kt
index 654a1919..6cecc108 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/ChatsActivity.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/ChatsActivity.kt
@@ -135,13 +135,13 @@ class ChatsActivity: AppCompatActivity() {
             }
         }
 
-        val peer = intent.extras.getString("peer")
+        val peer = intent.getStringExtra("peer")
         if (peer != "") {
             val i = Intent(this, ChatActivity::class.java)
             val b = Bundle()
             b.putString("aor", aor)
             b.putString("peer", peer)
-            b.putBoolean("focus", intent.extras.getBoolean("focus"))
+            b.putBoolean("focus", intent.getBooleanExtra("focus", false))
             i.putExtras(b)
             startActivityForResult(i, MainActivity.MESSAGE_CODE)
         }
diff --git a/app/src/main/kotlin/com/tutpro/baresip/ContactActivity.kt b/app/src/main/kotlin/com/tutpro/baresip/ContactActivity.kt
index aa2a20e8..565dbd27 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/ContactActivity.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/ContactActivity.kt
@@ -21,8 +21,8 @@ class ContactActivity : AppCompatActivity() {
         nameView = findViewById(R.id.Name) as EditText
         uriView = findViewById(R.id.Uri) as EditText
 
-        val uri = intent.extras.getString("uri")
-        new = intent.extras.getBoolean("new")
+        val uri = intent.getStringExtra("uri")
+        new = intent.getBooleanExtra("new", false)
 
         if (new) {
             setTitle("New Contact")
@@ -36,7 +36,7 @@ class ContactActivity : AppCompatActivity() {
                 uriView.setText(uri)
             }
         } else {
-            index = intent.extras.getInt("index")
+            index = intent.getIntExtra("index", 0)
             val name = Contact.contacts()[index].name
             setTitle(name)
             nameView.setText(name)
diff --git a/app/src/main/kotlin/com/tutpro/baresip/ContactsActivity.kt b/app/src/main/kotlin/com/tutpro/baresip/ContactsActivity.kt
index 6aba1c59..08e14cee 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/ContactsActivity.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/ContactsActivity.kt
@@ -23,7 +23,7 @@ class ContactsActivity : AppCompatActivity() {
 
         val listView = findViewById(R.id.contacts) as ListView
 
-        val aor = intent.extras.getString("aor")
+        val aor = intent.getStringExtra("aor")!!
         clAdapter = ContactListAdapter(this, Contact.contacts(), aor)
         listView.adapter = clAdapter
         listView.isLongClickable = true