diff --git a/app/src/main/java/ch/dissem/apps/abit/ComposeMessageActivity.kt b/app/src/main/java/ch/dissem/apps/abit/ComposeMessageActivity.kt
index ea9828c..a900abf 100644
--- a/app/src/main/java/ch/dissem/apps/abit/ComposeMessageActivity.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/ComposeMessageActivity.kt
@@ -98,7 +98,8 @@ class ComposeMessageActivity : AppCompatActivity() {
                 val prefix: String = if (subject.length >= 3 && subject.substring(0, 3).equals(
                         "RE:",
                         ignoreCase = true
-                    )) {
+                    )
+                ) {
                     ""
                 } else {
                     "RE: "
@@ -107,7 +108,7 @@ class ComposeMessageActivity : AppCompatActivity() {
             }
             replyIntent.putExtra(
                 EXTRA_CONTENT,
-                "\n\n------------------------------------------------------\n" + item.text!!
+                "\n\n------------------------------------------------------\n${item.text ?: ""}"
             )
             return replyIntent
         }
diff --git a/app/src/main/java/ch/dissem/apps/abit/MessageListFragment.kt b/app/src/main/java/ch/dissem/apps/abit/MessageListFragment.kt
index f4eac98..6597810 100644
--- a/app/src/main/java/ch/dissem/apps/abit/MessageListFragment.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/MessageListFragment.kt
@@ -79,7 +79,8 @@ class MessageListFragment : Fragment(), ListHolder<Label> {
 
                 if (!isLoading && !isLastPage) {
                     if (visibleItemCount + firstVisibleItemPosition >= totalItemCount - 5
-                        && firstVisibleItemPosition >= 0) {
+                        && firstVisibleItemPosition >= 0
+                    ) {
                         loadMoreItems()
                     }
                 }
diff --git a/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.kt b/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.kt
index 9d61984..20d0877 100644
--- a/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.kt
@@ -20,7 +20,6 @@ import android.app.Activity
 import android.content.*
 import android.os.Bundle
 import android.os.IBinder
-import android.preference.PreferenceManager
 import android.support.v4.app.Fragment
 import android.support.v4.content.ContextCompat
 import android.support.v4.content.FileProvider.getUriForFile
@@ -173,11 +172,12 @@ class SettingsFragment : PreferenceFragmentCompat(), SharedPreferences.OnSharedP
 
     override fun onAttach(ctx: Context?) {
         super.onAttach(ctx)
-        (ctx as? MainActivity)?.floatingActionButton?.hide()
-        PreferenceManager.getDefaultSharedPreferences(ctx)
-            .registerOnSharedPreferenceChangeListener(this)
-
-        (ctx as? MainActivity)?.updateTitle(getString(R.string.settings))
+        ctx?.let {
+            if (it is MainActivity) {
+                it.floatingActionButton?.hide()
+                it.updateTitle(getString(R.string.settings))
+            }
+        }
     }
 
     override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
diff --git a/app/src/main/res/xml/preferences.xml b/app/src/main/res/xml/preferences.xml
index 9ec7b51..bb4b957 100644
--- a/app/src/main/res/xml/preferences.xml
+++ b/app/src/main/res/xml/preferences.xml
@@ -1,105 +1,105 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.v7.preference.PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
+<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <android.support.v7.preference.PreferenceScreen
+    <PreferenceScreen
         android:key="preference_ux"
         android:title="@string/preference_group_user_experience"
         android:summary="@string/preference_group_user_experience_summary"
         android:persistent="false">
 
-        <android.support.v7.preference.SwitchPreferenceCompat
+        <SwitchPreferenceCompat
             android:defaultValue="true"
             android:key="emulate_conversations"
             android:summary="@string/emulate_conversations_summary"
             android:title="@string/emulate_conversations" />
-        <android.support.v7.preference.Preference
+        <Preference
             android:defaultValue="true"
             android:key="emulate_conversations_initialize"
             android:summary="@string/emulate_conversations_summary"
             android:title="@string/emulate_conversations_initialize" />
 
-    </android.support.v7.preference.PreferenceScreen>
+    </PreferenceScreen>
 
-    <android.support.v7.preference.PreferenceScreen
+    <PreferenceScreen
         android:key="preference_network_and_performance"
         android:title="@string/preference_group_network_and_performance"
         android:summary="@string/preference_group_network_and_performance_summary"
         android:persistent="false">
 
-        <android.support.v7.preference.SwitchPreferenceCompat
+        <SwitchPreferenceCompat
             android:defaultValue="true"
             android:key="wifi_only"
             android:summary="@string/wifi_only_summary"
             android:title="@string/wifi_only" />
-        <android.support.v7.preference.SwitchPreferenceCompat
+        <SwitchPreferenceCompat
             android:defaultValue="true"
             android:key="request_acknowledgements"
             android:summary="@string/request_acknowledgements_summary"
             android:title="@string/request_acknowledgements" />
 
-    </android.support.v7.preference.PreferenceScreen>
+    </PreferenceScreen>
 
-    <android.support.v7.preference.PreferenceScreen
+    <PreferenceScreen
         android:key="preference_advanced"
         android:title="@string/preference_group_advanced"
         android:summary="@string/preference_group_advanced_summary"
         android:persistent="false">
 
-        <android.support.v7.preference.Preference
+        <Preference
             android:key="cleanup"
             android:summary="@string/cleanup_summary"
             android:title="@string/cleanup" />
-        <android.support.v7.preference.Preference
+        <Preference
             android:key="export"
             android:summary="@string/export_data_summary"
             android:title="@string/export_data" />
-        <android.support.v7.preference.Preference
+        <Preference
             android:key="import"
             android:summary="@string/import_data_summary"
             android:title="@string/import_data" />
 
-        <android.support.v7.preference.PreferenceScreen
+        <PreferenceScreen
             android:key="preference_experimental"
             android:title="@string/preference_group_experimental"
             android:summary="@string/preference_group_experimental_summary"
             android:persistent="false">
 
-            <android.support.v7.preference.EditTextPreference
+            <EditTextPreference
                 android:inputType="textUri"
                 android:key="trusted_node"
                 android:summary="@string/trusted_node_summary"
                 android:title="@string/trusted_node" />
-            <android.support.v7.preference.EditTextPreference
+            <EditTextPreference
                 android:defaultValue="120"
                 android:inputType="number"
                 android:key="sync_timeout"
                 android:summary="@string/sync_timeout_summary"
                 android:title="@string/sync_timeout" />
-            <android.support.v7.preference.SwitchPreferenceCompat
+            <SwitchPreferenceCompat
                 android:defaultValue="false"
                 android:dependency="trusted_node"
                 android:key="server_pow"
                 android:summary="@string/server_pow_summary"
                 android:title="@string/server_pow" />
-            <android.support.v7.preference.Preference
+            <Preference
                 android:key="status"
                 android:summary="@string/status_summary"
                 android:title="@string/status" />
 
-        </android.support.v7.preference.PreferenceScreen>
+        </PreferenceScreen>
 
-    </android.support.v7.preference.PreferenceScreen>
+    </PreferenceScreen>
 
-    <android.support.v7.preference.Preference
+    <Preference
         android:key="about"
         android:summary="@string/about_summary"
         android:title="@string/about" />
-    <android.support.v7.preference.Preference
+    <Preference
         android:key="help_out"
         android:summary="@string/help_out_summary"
         android:title="@string/help_out">
         <intent
             android:action="android.intent.action.VIEW"
             android:data="@string/help_out_link" />
-    </android.support.v7.preference.Preference>
-</android.support.v7.preference.PreferenceScreen>
+    </Preference>
+</PreferenceScreen>