diff --git a/src/main/kotlin/org/koitharu/kotatsu/parsers/site/ComickFunParser.kt b/src/main/kotlin/org/koitharu/kotatsu/parsers/site/ComickFunParser.kt
index 5028c0ff..ae7a92b2 100644
--- a/src/main/kotlin/org/koitharu/kotatsu/parsers/site/ComickFunParser.kt
+++ b/src/main/kotlin/org/koitharu/kotatsu/parsers/site/ComickFunParser.kt
@@ -9,10 +9,7 @@ import org.koitharu.kotatsu.parsers.MangaParser
 import org.koitharu.kotatsu.parsers.config.ConfigKey
 import org.koitharu.kotatsu.parsers.model.*
 import org.koitharu.kotatsu.parsers.util.*
-import org.koitharu.kotatsu.parsers.util.json.JSONIterator
-import org.koitharu.kotatsu.parsers.util.json.getStringOrNull
-import org.koitharu.kotatsu.parsers.util.json.mapJSON
-import org.koitharu.kotatsu.parsers.util.json.mapJSONToSet
+import org.koitharu.kotatsu.parsers.util.json.*
 import java.text.SimpleDateFormat
 import java.util.*
 
@@ -82,7 +79,7 @@ internal class ComickFunParser(override val context: MangaLoaderContext) : Manga
 				altTitle = null,
 				url = slug,
 				publicUrl = "https://$domain/comic/$slug",
-				rating = jo.optDouble("rating", -10.0).toFloat() / 10f,
+				rating = jo.getDoubleOrDefault("rating", -10.0).toFloat() / 10f,
 				isNsfw = false,
 				coverUrl = jo.getString("cover_url"),
 				largeCoverUrl = null,
diff --git a/src/main/kotlin/org/koitharu/kotatsu/parsers/site/MangaDexParser.kt b/src/main/kotlin/org/koitharu/kotatsu/parsers/site/MangaDexParser.kt
index fe107df3..2049c07a 100644
--- a/src/main/kotlin/org/koitharu/kotatsu/parsers/site/MangaDexParser.kt
+++ b/src/main/kotlin/org/koitharu/kotatsu/parsers/site/MangaDexParser.kt
@@ -151,7 +151,7 @@ internal class MangaDexParser(override val context: MangaLoaderContext) : MangaP
 				}
 				val locale = Locale.forLanguageTag(attrs.getString("translatedLanguage"))
 				val relations = jo.getJSONArray("relationships").associateByKey("type")
-				val number = attrs.optInt("chapter", 0)
+				val number = attrs.getIntOrDefault("chapter", 0)
 				MangaChapter(
 					id = generateUid(id),
 					name = attrs.getStringOrNull("title")?.takeUnless(String::isEmpty)
diff --git a/src/main/kotlin/org/koitharu/kotatsu/parsers/util/json/JsonExt.kt b/src/main/kotlin/org/koitharu/kotatsu/parsers/util/json/JsonExt.kt
index 066a8cd0..4e27a336 100644
--- a/src/main/kotlin/org/koitharu/kotatsu/parsers/util/json/JsonExt.kt
+++ b/src/main/kotlin/org/koitharu/kotatsu/parsers/util/json/JsonExt.kt
@@ -6,6 +6,7 @@ import org.json.JSONObject
 import org.koitharu.kotatsu.utils.json.JSONIterator
 import org.koitharu.kotatsu.utils.json.JSONStringIterator
 import org.koitharu.kotatsu.utils.json.JSONValuesIterator
+import java.util.*
 import kotlin.contracts.contract
 
 inline fun <R, C : MutableCollection<in R>> JSONArray.mapJSONTo(
@@ -56,13 +57,45 @@ fun JSONObject.getStringOrNull(name: String): String? = opt(name)?.takeUnless {
 	it.isEmpty()
 }
 
-fun JSONObject.getBooleanOrDefault(name: String, defaultValue: Boolean): Boolean = opt(name)?.takeUnless {
-	it === JSONObject.NULL
-} as? Boolean ?: defaultValue
+fun JSONObject.getBooleanOrDefault(name: String, defaultValue: Boolean): Boolean {
+	return when (val rawValue = opt(name)) {
+		null, JSONObject.NULL -> defaultValue
+		is Boolean -> rawValue
+		is Number -> rawValue.toInt() != 0
+		is String -> rawValue.lowercase(Locale.ROOT).toBooleanStrictOrNull() ?: defaultValue
+		else -> defaultValue
+	}
+}
 
-fun JSONObject.getLongOrDefault(name: String, defaultValue: Long): Long = opt(name)?.takeUnless {
-	it === JSONObject.NULL
-} as? Long ?: defaultValue
+fun JSONObject.getLongOrDefault(name: String, defaultValue: Long): Long {
+	return when (val rawValue = opt(name)) {
+		null, JSONObject.NULL -> defaultValue
+		is Long -> rawValue
+		is Number -> rawValue.toLong()
+		is String -> rawValue.toLongOrNull() ?: defaultValue
+		else -> defaultValue
+	}
+}
+
+fun JSONObject.getIntOrDefault(name: String, defaultValue: Int): Int {
+	return when (val rawValue = opt(name)) {
+		null, JSONObject.NULL -> defaultValue
+		is Int -> rawValue
+		is Number -> rawValue.toInt()
+		is String -> rawValue.toIntOrNull() ?: defaultValue
+		else -> defaultValue
+	}
+}
+
+fun JSONObject.getDoubleOrDefault(name: String, defaultValue: Double): Double {
+	return when (val rawValue = opt(name)) {
+		null, JSONObject.NULL -> defaultValue
+		is Double -> rawValue
+		is Number -> rawValue.toDouble()
+		is String -> rawValue.toDoubleOrNull() ?: defaultValue
+		else -> defaultValue
+	}
+}
 
 fun JSONArray.JSONIterator(): Iterator<JSONObject> = JSONIterator(this)