diff --git a/src/com/android/calendar/AllInOneActivity.kt b/src/com/android/calendar/AllInOneActivity.kt
index b3b45fc..d6767f0 100644
--- a/src/com/android/calendar/AllInOneActivity.kt
+++ b/src/com/android/calendar/AllInOneActivity.kt
@@ -683,7 +683,7 @@
     }
 
     @Override
-    override fun onSharedPreferenceChanged(prefs: SharedPreferences?, key: String) {
+    override fun onSharedPreferenceChanged(prefs: SharedPreferences, key: String?) {
         if (key.equals(GeneralPreferences.KEY_WEEK_START_DAY)) {
             if (mPaused) {
                 mUpdateOnResume = true
diff --git a/src/com/android/calendar/GeneralPreferences.kt b/src/com/android/calendar/GeneralPreferences.kt
index 9406eff..4044ef1 100644
--- a/src/com/android/calendar/GeneralPreferences.kt
+++ b/src/com/android/calendar/GeneralPreferences.kt
@@ -172,7 +172,7 @@
     }
 
     @Override
-    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String) {
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String?) {
         val a: Activity = getActivity()
         if (key.equals(KEY_ALERTS)) {
             updateChildPreferences()
diff --git a/src/com/android/calendar/alerts/AlertUtils.kt b/src/com/android/calendar/alerts/AlertUtils.kt
index 18b7e7d..21b2be0 100644
--- a/src/com/android/calendar/alerts/AlertUtils.kt
+++ b/src/com/android/calendar/alerts/AlertUtils.kt
@@ -53,9 +53,9 @@
         return object : AlarmManagerInterface {
             override operator fun set(type: Int, triggerAtMillis: Long, operation: PendingIntent?) {
                 if (com.android.calendar.Utils.isKeyLimePieOrLater()) {
-                    mgr.setExact(type, triggerAtMillis, operation)
+                    mgr.setExact(type, triggerAtMillis, operation!!)
                 } else {
-                    mgr.set(type, triggerAtMillis, operation)
+                    mgr.set(type, triggerAtMillis, operation!!)
                 }
             }
         }