diff --git a/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadCache.kt b/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadCache.kt
index efeb9e4163..9fe7dbfeed 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadCache.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadCache.kt
@@ -40,6 +40,8 @@ import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
 import kotlinx.serialization.protobuf.ProtoBuf
 import logcat.LogPriority
+import tachiyomi.core.storage.extension
+import tachiyomi.core.storage.nameWithoutExtension
 import tachiyomi.core.util.lang.launchIO
 import tachiyomi.core.util.lang.launchNonCancellable
 import tachiyomi.core.util.system.logcat
@@ -351,8 +353,7 @@ class DownloadCache(
                                             // Folder of images
                                             it.isDirectory -> it.name
                                             // CBZ files
-                                            it.isFile && it.name?.endsWith(".cbz") == true ->
-                                                it.name!!.substringBeforeLast(".cbz")
+                                            it.isFile && it.extension == "cbz" -> it.nameWithoutExtension
                                             // Anything else is irrelevant
                                             else -> null
                                         }
diff --git a/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.kt b/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.kt
index 0b404165fc..ba5c4d81a9 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.kt
@@ -15,6 +15,7 @@ import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.runBlocking
 import logcat.LogPriority
 import tachiyomi.core.i18n.stringResource
+import tachiyomi.core.storage.extension
 import tachiyomi.core.util.lang.launchIO
 import tachiyomi.core.util.system.logcat
 import tachiyomi.domain.category.interactor.GetCategories
@@ -340,7 +341,7 @@ class DownloadManager(
             .firstOrNull() ?: return
 
         var newName = provider.getChapterDirName(newChapter.name, newChapter.scanlator)
-        if (oldDownload.isFile && oldDownload.name?.endsWith(".cbz") == true) {
+        if (oldDownload.isFile && oldDownload.extension == "cbz") {
             newName += ".cbz"
         }
 
diff --git a/app/src/main/java/eu/kanade/tachiyomi/data/download/Downloader.kt b/app/src/main/java/eu/kanade/tachiyomi/data/download/Downloader.kt
index f89146e3a0..74a90b3ba8 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/data/download/Downloader.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/data/download/Downloader.kt
@@ -43,6 +43,7 @@ import okhttp3.Response
 import tachiyomi.core.i18n.stringResource
 import tachiyomi.core.metadata.comicinfo.COMIC_INFO_FILE
 import tachiyomi.core.metadata.comicinfo.ComicInfo
+import tachiyomi.core.storage.extension
 import tachiyomi.core.util.lang.launchIO
 import tachiyomi.core.util.lang.launchNow
 import tachiyomi.core.util.lang.withIOContext
@@ -353,7 +354,7 @@ class Downloader(
 
             // Delete all temporary (unfinished) files
             tmpDir.listFiles()
-                ?.filter { it.name!!.endsWith(".tmp") }
+                ?.filter { it.extension == "tmp" }
                 ?.forEach { it.delete() }
 
             download.status = Download.State.DOWNLOADING
diff --git a/core/src/main/java/tachiyomi/core/storage/UniFileExtensions.kt b/core/src/main/java/tachiyomi/core/storage/UniFileExtensions.kt
new file mode 100644
index 0000000000..9a869c8835
--- /dev/null
+++ b/core/src/main/java/tachiyomi/core/storage/UniFileExtensions.kt
@@ -0,0 +1,9 @@
+package tachiyomi.core.storage
+
+import com.hippo.unifile.UniFile
+
+val UniFile.extension: String?
+    get() = name?.substringAfterLast('.')
+
+val UniFile.nameWithoutExtension: String?
+    get() = name?.substringBeforeLast('.')