diff --git a/twidere/src/main/kotlin/org/mariotaku/twidere/activity/SignInActivity.kt b/twidere/src/main/kotlin/org/mariotaku/twidere/activity/SignInActivity.kt
index f04c95635..027b4d426 100644
--- a/twidere/src/main/kotlin/org/mariotaku/twidere/activity/SignInActivity.kt
+++ b/twidere/src/main/kotlin/org/mariotaku/twidere/activity/SignInActivity.kt
@@ -73,7 +73,6 @@ import org.mariotaku.twidere.model.ParcelableCredentials.AuthType
 import org.mariotaku.twidere.model.util.ParcelableAccountUtils
 import org.mariotaku.twidere.model.util.ParcelableUserUtils
 import org.mariotaku.twidere.model.util.UserKeyUtils
-import org.mariotaku.twidere.provider.TwidereDataStore
 import org.mariotaku.twidere.provider.TwidereDataStore.Accounts
 import org.mariotaku.twidere.util.*
 import org.mariotaku.twidere.util.OAuthPasswordAuthenticator.*
@@ -378,16 +377,16 @@ class SignInActivity : BaseActivity(), OnClickListener, TextWatcher {
                 if (values != null) {
                     val where = Expression.equalsArgs(Accounts.ACCOUNT_KEY).sql
                     val whereArgs = arrayOf(values.getAsString(Accounts.ACCOUNT_KEY))
-                    contentResolver!!.update(Accounts.CONTENT_URI, values, where, whereArgs)
+                    contentResolver.update(Accounts.CONTENT_URI, values, where, whereArgs)
                 }
                 Toast.makeText(this, R.string.error_already_logged_in, Toast.LENGTH_SHORT).show()
             } else if (result.succeed) {
                 val values = result.toContentValues()
                 if (values != null) {
-                    contentResolver!!.insert(Accounts.CONTENT_URI, values)
+                    contentResolver.insert(Accounts.CONTENT_URI, values)
                 }
                 val intent = Intent(this, HomeActivity::class.java)
-                //TODO refresh timelines
+                //TODO refresh time lines
                 intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT)
                 startActivity(intent)
                 finish()
@@ -433,13 +432,12 @@ class SignInActivity : BaseActivity(), OnClickListener, TextWatcher {
 
     internal fun showSignInProgressDialog() {
         executeAfterFragmentResumed {
-            if (isFinishing) return@executeAfterFragmentResumed Unit
+            if (isFinishing) return@executeAfterFragmentResumed
             val fm = supportFragmentManager
             val ft = fm.beginTransaction()
             val fragment = ProgressDialogFragment()
             fragment.isCancelable = false
             fragment.show(ft, FRAGMENT_TAG_SIGN_IN_PROGRESS)
-            Unit
         }
     }
 
diff --git a/twidere/src/main/kotlin/org/mariotaku/twidere/fragment/AbsActivitiesFragment.kt b/twidere/src/main/kotlin/org/mariotaku/twidere/fragment/AbsActivitiesFragment.kt
index 99d26b8b1..e7f3e70b1 100644
--- a/twidere/src/main/kotlin/org/mariotaku/twidere/fragment/AbsActivitiesFragment.kt
+++ b/twidere/src/main/kotlin/org/mariotaku/twidere/fragment/AbsActivitiesFragment.kt
@@ -113,6 +113,15 @@ abstract class AbsActivitiesFragment protected constructor() : AbsContentListRec
         }
     }
 
+    private val onScrollListener = object : OnScrollListener() {
+        override fun onScrollStateChanged(recyclerView: RecyclerView?, newState: Int) {
+            if (newState == RecyclerView.SCROLL_STATE_IDLE) {
+                val layoutManager = layoutManager ?: return
+                saveReadPosition(layoutManager.findFirstVisibleItemPosition())
+            }
+        }
+    }
+
     private var navigationHelper: RecyclerViewNavigationHelper? = null
     private var pauseOnScrollListener: OnScrollListener? = null
     private var activeHotMobiScrollTracker: OnScrollListener? = null
@@ -373,6 +382,7 @@ abstract class AbsActivitiesFragment protected constructor() : AbsContentListRec
 
     override fun onStart() {
         super.onStart()
+        recyclerView.addOnScrollListener(onScrollListener)
         recyclerView.addOnScrollListener(pauseOnScrollListener)
         val task = object : AbstractTask<Any?, Boolean, RecyclerView>() {
             public override fun doLongOperation(params: Any?): Boolean {
@@ -403,6 +413,7 @@ abstract class AbsActivitiesFragment protected constructor() : AbsContentListRec
         }
         activeHotMobiScrollTracker = null
         recyclerView.removeOnScrollListener(pauseOnScrollListener)
+        recyclerView.removeOnScrollListener(onScrollListener)
         if (userVisibleHint) {
             saveReadPosition()
         }
diff --git a/twidere/src/main/kotlin/org/mariotaku/twidere/fragment/AbsStatusesFragment.kt b/twidere/src/main/kotlin/org/mariotaku/twidere/fragment/AbsStatusesFragment.kt
index 1f62293e2..37cc5b55d 100644
--- a/twidere/src/main/kotlin/org/mariotaku/twidere/fragment/AbsStatusesFragment.kt
+++ b/twidere/src/main/kotlin/org/mariotaku/twidere/fragment/AbsStatusesFragment.kt
@@ -117,8 +117,8 @@ abstract class AbsStatusesFragment protected constructor() :
     private val onScrollListener = object : OnScrollListener() {
         override fun onScrollStateChanged(recyclerView: RecyclerView?, newState: Int) {
             if (newState == RecyclerView.SCROLL_STATE_IDLE) {
-                val layoutManager = layoutManager
-                saveReadPosition(layoutManager!!.findFirstVisibleItemPosition())
+                val layoutManager = layoutManager ?: return
+                saveReadPosition(layoutManager.findFirstVisibleItemPosition())
             }
         }
     }