diff --git a/twidere/src/main/kotlin/org/mariotaku/ktextension/CursorExtensions.kt b/twidere/src/main/kotlin/org/mariotaku/ktextension/CursorExtensions.kt
index ac6952906..34c70b59b 100644
--- a/twidere/src/main/kotlin/org/mariotaku/ktextension/CursorExtensions.kt
+++ b/twidere/src/main/kotlin/org/mariotaku/ktextension/CursorExtensions.kt
@@ -26,7 +26,7 @@ fun Cursor.safeGetInt(columnIndex: Int, def: Int = -1) = try {
     def
 }
 
-fun Cursor.safeGetString(columnIndex: Int, def: String = "") = try {
+fun Cursor.safeGetString(columnIndex: Int, def: String = ""): String = try {
     getString(columnIndex)
 } catch (e: IllegalStateException) {
     def
diff --git a/twidere/src/main/kotlin/org/mariotaku/twidere/extension/mime4j/ContentTypeFieldExtensions.kt b/twidere/src/main/kotlin/org/mariotaku/twidere/extension/mime4j/ContentTypeFieldExtensions.kt
index b8db4482b..d45fb1c01 100644
--- a/twidere/src/main/kotlin/org/mariotaku/twidere/extension/mime4j/ContentTypeFieldExtensions.kt
+++ b/twidere/src/main/kotlin/org/mariotaku/twidere/extension/mime4j/ContentTypeFieldExtensions.kt
@@ -30,5 +30,5 @@ fun ContentTypeField.getIntParameter(name: String, def: Int): Int {
 }
 
 fun ContentTypeField.getBooleanParameter(name: String): Boolean {
-    return getParameter(name).toBoolean()
+    return this.getParameter(name)!!.toBoolean()
 }
\ No newline at end of file
diff --git a/twidere/src/main/kotlin/org/mariotaku/twidere/extension/model/ParcelableCardEntityExtensions.kt b/twidere/src/main/kotlin/org/mariotaku/twidere/extension/model/ParcelableCardEntityExtensions.kt
index e4b26e71d..3725cbe96 100644
--- a/twidere/src/main/kotlin/org/mariotaku/twidere/extension/model/ParcelableCardEntityExtensions.kt
+++ b/twidere/src/main/kotlin/org/mariotaku/twidere/extension/model/ParcelableCardEntityExtensions.kt
@@ -46,7 +46,7 @@ fun CardEntity.toParcelable(accountKey: UserKey, accountType: String): Parcelabl
 
 fun ParcelableCardEntity.getAsBoolean(key: String, def: Boolean): Boolean {
     val value = getValue(key) ?: return def
-    return value.value.toBoolean()
+    return value.value!!.toBoolean()
 }
 
 fun ParcelableCardEntity.getAsString(key: String, def: String?): String? {