diff --git a/app/build.gradle b/app/build.gradle
index 96f89da3d..490d40938 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -82,7 +82,7 @@ afterEvaluate {
 }
 dependencies {
 	//noinspection GradleDependency
-	implementation('com.github.KotatsuApp:kotatsu-parsers:8852d1e22e') {
+	implementation('com.github.KotatsuApp:kotatsu-parsers:a8f9423307') {
 		exclude group: 'org.json', module: 'json'
 	}
 
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/core/model/Manga.kt b/app/src/main/kotlin/org/koitharu/kotatsu/core/model/Manga.kt
index d2b579b10..f98d055ae 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/core/model/Manga.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/core/model/Manga.kt
@@ -13,6 +13,8 @@ import org.koitharu.kotatsu.parsers.model.MangaChapter
 import org.koitharu.kotatsu.parsers.model.MangaSource
 import org.koitharu.kotatsu.parsers.model.MangaState
 import org.koitharu.kotatsu.parsers.util.mapToSet
+import java.text.DecimalFormat
+import java.text.DecimalFormatSymbols
 import com.google.android.material.R as materialR
 
 @JvmName("mangaIds")
@@ -113,3 +115,16 @@ val Manga.appUrl: Uri
 		.appendQueryParameter("name", title)
 		.appendQueryParameter("url", url)
 		.build()
+
+private val chaptersNumberFormat = DecimalFormat("#.#").also { f ->
+	f.decimalFormatSymbols = DecimalFormatSymbols.getInstance().also {
+		it.decimalSeparator = '.'
+	}
+}
+
+fun MangaChapter.formatNumber(): String? {
+	if (number <= 0f) {
+		return null
+	}
+	return chaptersNumberFormat.format(number.toDouble())
+}
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/core/model/parcelable/ParcelableChapter.kt b/app/src/main/kotlin/org/koitharu/kotatsu/core/model/parcelable/ParcelableChapter.kt
index 190185bdd..3eb99abdc 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/core/model/parcelable/ParcelableChapter.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/core/model/parcelable/ParcelableChapter.kt
@@ -19,7 +19,8 @@ data class ParcelableChapter(
 			MangaChapter(
 				id = parcel.readLong(),
 				name = parcel.readString().orEmpty(),
-				number = parcel.readInt(),
+				number = parcel.readFloat(),
+				volume = parcel.readInt(),
 				url = parcel.readString().orEmpty(),
 				scanlator = parcel.readString(),
 				uploadDate = parcel.readLong(),
@@ -31,7 +32,8 @@ data class ParcelableChapter(
 		override fun ParcelableChapter.write(parcel: Parcel, flags: Int) = with(chapter) {
 			parcel.writeLong(id)
 			parcel.writeString(name)
-			parcel.writeInt(number)
+			parcel.writeFloat(number)
+			parcel.writeInt(volume)
 			parcel.writeString(url)
 			parcel.writeString(scanlator)
 			parcel.writeLong(uploadDate)
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/details/ui/model/ChapterListItem.kt b/app/src/main/kotlin/org/koitharu/kotatsu/details/ui/model/ChapterListItem.kt
index 55cbdccd5..518dcc800 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/details/ui/model/ChapterListItem.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/details/ui/model/ChapterListItem.kt
@@ -2,6 +2,7 @@ package org.koitharu.kotatsu.details.ui.model
 
 import android.text.format.DateUtils
 import org.jsoup.internal.StringUtil.StringJoiner
+import org.koitharu.kotatsu.core.model.formatNumber
 import org.koitharu.kotatsu.list.ui.model.ListModel
 import org.koitharu.kotatsu.parsers.model.MangaChapter
 
@@ -49,8 +50,8 @@ data class ChapterListItem(
 
 	private fun buildDescription(): String {
 		val joiner = StringJoiner(" • ")
-		if (chapter.number != 0) {
-			joiner.add("#").append(chapter.number.toString())
+		chapter.formatNumber()?.let {
+			joiner.add("#").append(it)
 		}
 		uploadDate?.let { date ->
 			joiner.add(date.toString())
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/download/ui/list/DownloadsViewModel.kt b/app/src/main/kotlin/org/koitharu/kotatsu/download/ui/list/DownloadsViewModel.kt
index 96a884748..8844e3293 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/download/ui/list/DownloadsViewModel.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/download/ui/list/DownloadsViewModel.kt
@@ -21,6 +21,7 @@ import kotlinx.coroutines.plus
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import org.koitharu.kotatsu.R
+import org.koitharu.kotatsu.core.model.formatNumber
 import org.koitharu.kotatsu.core.parser.MangaDataRepository
 import org.koitharu.kotatsu.core.parser.MangaRepository
 import org.koitharu.kotatsu.core.parser.RemoteMangaRepository
@@ -306,7 +307,7 @@ class DownloadsViewModel @Inject constructor(
 			return chapters.mapNotNullTo(ArrayList(size)) {
 				if (chapterIds == null || it.id in chapterIds) {
 					DownloadChapter(
-						number = it.number,
+						number = it.formatNumber(),
 						name = it.name,
 						isDownloaded = it.id in localChapters,
 					)
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/download/ui/list/chapters/DownloadChapter.kt b/app/src/main/kotlin/org/koitharu/kotatsu/download/ui/list/chapters/DownloadChapter.kt
index a9e2b3577..5a77ae407 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/download/ui/list/chapters/DownloadChapter.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/download/ui/list/chapters/DownloadChapter.kt
@@ -4,7 +4,7 @@ import org.koitharu.kotatsu.list.ui.ListModelDiffCallback
 import org.koitharu.kotatsu.list.ui.model.ListModel
 
 data class DownloadChapter(
-	val number: Int,
+	val number: String?,
 	val name: String,
 	val isDownloaded: Boolean,
 ) : ListModel {
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/MangaIndex.kt b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/MangaIndex.kt
index 36368fddf..5bb6be433 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/MangaIndex.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/MangaIndex.kt
@@ -12,6 +12,8 @@ import org.koitharu.kotatsu.parsers.model.MangaState
 import org.koitharu.kotatsu.parsers.model.MangaTag
 import org.koitharu.kotatsu.parsers.util.find
 import org.koitharu.kotatsu.parsers.util.json.getBooleanOrDefault
+import org.koitharu.kotatsu.parsers.util.json.getFloatOrDefault
+import org.koitharu.kotatsu.parsers.util.json.getIntOrDefault
 import org.koitharu.kotatsu.parsers.util.json.getLongOrDefault
 import org.koitharu.kotatsu.parsers.util.json.getStringOrNull
 import org.koitharu.kotatsu.parsers.util.json.mapJSONToSet
@@ -91,6 +93,7 @@ class MangaIndex(source: String?) {
 		if (!chapters.has(chapter.id.toString())) {
 			val jo = JSONObject()
 			jo.put("number", chapter.number)
+			jo.put("volume", chapter.volume)
 			jo.put("url", chapter.url)
 			jo.put("name", chapter.name)
 			jo.put("uploadDate", chapter.uploadDate)
@@ -162,7 +165,8 @@ class MangaIndex(source: String?) {
 					id = k.toLong(),
 					name = v.getString("name"),
 					url = v.getString("url"),
-					number = v.getInt("number"),
+					number = v.getFloatOrDefault("number", 0f),
+					volume = v.getIntOrDefault("volume", 0),
 					uploadDate = v.getLongOrDefault("uploadDate", 0L),
 					scanlator = v.getStringOrNull("scanlator"),
 					branch = v.getStringOrNull("branch"),
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaDirInput.kt b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaDirInput.kt
index 6ac62b8de..dcf416efc 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaDirInput.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaDirInput.kt
@@ -71,7 +71,8 @@ class LocalMangaDirInput(root: File) : LocalMangaInput(root) {
 				MangaChapter(
 					id = "$i${f.name}".longHashCode(),
 					name = f.nameWithoutExtension.toHumanReadable(),
-					number = i + 1,
+					number = 0f,
+					volume = 0,
 					source = MangaSource.LOCAL,
 					uploadDate = f.creationTime,
 					url = f.toUri().toString(),
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaInput.kt b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaInput.kt
index 45454631a..13d129235 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaInput.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaInput.kt
@@ -100,6 +100,7 @@ sealed class LocalMangaInput(
 			id = id,
 			name = name,
 			number = number,
+			volume = volume,
 			url = url,
 			scanlator = scanlator,
 			uploadDate = uploadDate,
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaZipInput.kt b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaZipInput.kt
index cc679b7b6..02b4bcf8a 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaZipInput.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/input/LocalMangaZipInput.kt
@@ -76,7 +76,8 @@ class LocalMangaZipInput(root: File) : LocalMangaInput(root) {
 							MangaChapter(
 								id = "$i$s".longHashCode(),
 								name = s.ifEmpty { title },
-								number = i + 1,
+								number = 0f,
+								volume = 0,
 								source = MangaSource.LOCAL,
 								uploadDate = 0L,
 								url = uriBuilder.fragment(s).build().toString(),
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/ReaderViewModel.kt b/app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/ReaderViewModel.kt
index 03473f94f..700144283 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/ReaderViewModel.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/ReaderViewModel.kt
@@ -51,6 +51,7 @@ import org.koitharu.kotatsu.history.data.PROGRESS_NONE
 import org.koitharu.kotatsu.history.domain.HistoryUpdateUseCase
 import org.koitharu.kotatsu.parsers.model.Manga
 import org.koitharu.kotatsu.parsers.model.MangaPage
+import org.koitharu.kotatsu.parsers.util.assertNotNull
 import org.koitharu.kotatsu.reader.domain.ChaptersLoader
 import org.koitharu.kotatsu.reader.domain.DetectReaderModeUseCase
 import org.koitharu.kotatsu.reader.domain.PageLoader
@@ -381,18 +382,20 @@ class ReaderViewModel @Inject constructor(
 
 	@WorkerThread
 	private fun notifyStateChanged() {
-		val state = getCurrentState()
-		val chapter = state?.chapterId?.let { chaptersLoader.peekChapter(it) }
+		val state = getCurrentState().assertNotNull("state") ?: return
+		val chapter = chaptersLoader.peekChapter(state.chapterId).assertNotNull("chapter") ?: return
+		val m = manga.assertNotNull("manga") ?: return
+		val chapterIndex = m.chapters[chapter.branch]?.indexOf(chapter) ?: -1
 		val newState = ReaderUiState(
-			mangaName = manga?.toManga()?.title,
-			branch = chapter?.branch,
-			chapterName = chapter?.name,
-			chapterNumber = chapter?.number ?: 0,
-			chaptersTotal = manga?.chapters?.get(chapter?.branch)?.size ?: 0,
-			totalPages = if (chapter != null) chaptersLoader.getPagesCount(chapter.id) else 0,
-			currentPage = state?.page ?: 0,
+			mangaName = m.toManga().title,
+			branch = chapter.branch,
+			chapterName = chapter.name,
+			chapterNumber = chapterIndex + 1,
+			chaptersTotal = m.chapters[chapter.branch]?.size ?: 0,
+			totalPages = chaptersLoader.getPagesCount(chapter.id),
+			currentPage = state.page,
 			isSliderEnabled = settings.isReaderSliderEnabled,
-			percent = if (state != null) computePercent(state.chapterId, state.page) else PROGRESS_NONE,
+			percent = computePercent(state.chapterId, state.page),
 		)
 		uiState.value = newState
 	}