diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/core/backup/BackupZipInput.kt b/app/src/main/kotlin/org/koitharu/kotatsu/core/backup/BackupZipInput.kt
index 61da0c264..342f1640d 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/core/backup/BackupZipInput.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/core/backup/BackupZipInput.kt
@@ -6,12 +6,14 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.runInterruptible
 import okio.Closeable
 import org.json.JSONArray
+import org.koitharu.kotatsu.core.exceptions.BadBackupFormatException
 import org.koitharu.kotatsu.core.util.ext.processLifecycleScope
 import java.io.File
 import java.util.EnumSet
+import java.util.zip.ZipException
 import java.util.zip.ZipFile
 
-class BackupZipInput(val file: File) : Closeable {
+class BackupZipInput private constructor(val file: File) : Closeable {
 
 	private val zipFile = ZipFile(file)
 
@@ -41,4 +43,17 @@ class BackupZipInput(val file: File) : Closeable {
 			}
 		}
 	}
+
+	companion object {
+
+		fun from(file: File): BackupZipInput = try {
+			val res = BackupZipInput(file)
+			if (res.zipFile.getEntry("index") == null) {
+				throw BadBackupFormatException(null)
+			}
+			res
+		} catch (e: ZipException) {
+			throw BadBackupFormatException(e)
+		}
+	}
 }
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/core/exceptions/BadBackupFormatException.kt b/app/src/main/kotlin/org/koitharu/kotatsu/core/exceptions/BadBackupFormatException.kt
new file mode 100644
index 000000000..422d551d2
--- /dev/null
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/core/exceptions/BadBackupFormatException.kt
@@ -0,0 +1,5 @@
+package org.koitharu.kotatsu.core.exceptions
+
+import java.io.IOException
+
+class BadBackupFormatException(cause: Throwable?) : IOException(cause)
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/core/util/ext/Throwable.kt b/app/src/main/kotlin/org/koitharu/kotatsu/core/util/ext/Throwable.kt
index c19d76c6c..94726ef95 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/core/util/ext/Throwable.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/core/util/ext/Throwable.kt
@@ -10,6 +10,7 @@ import okio.IOException
 import org.acra.ktx.sendWithAcra
 import org.jsoup.HttpStatusException
 import org.koitharu.kotatsu.R
+import org.koitharu.kotatsu.core.exceptions.BadBackupFormatException
 import org.koitharu.kotatsu.core.exceptions.CaughtException
 import org.koitharu.kotatsu.core.exceptions.CloudFlareProtectedException
 import org.koitharu.kotatsu.core.exceptions.EmptyHistoryException
@@ -43,6 +44,7 @@ fun Throwable.getDisplayMessage(resources: Resources): String = when (this) {
 
 	is TooManyRequestExceptions -> resources.getString(R.string.too_many_requests_message)
 	is UnsupportedFileException -> resources.getString(R.string.text_file_not_supported)
+	is BadBackupFormatException -> resources.getString(R.string.unsupported_backup_message)
 	is FileNotFoundException -> resources.getString(R.string.file_not_found)
 	is AccessDeniedException -> resources.getString(R.string.no_access_to_file)
 	is EmptyHistoryException -> resources.getString(R.string.history_is_empty)
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt b/app/src/main/kotlin/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt
index 2de76928c..919728c4d 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt
@@ -13,7 +13,9 @@ import org.koitharu.kotatsu.core.backup.BackupRepository
 import org.koitharu.kotatsu.core.backup.BackupZipInput
 import org.koitharu.kotatsu.core.backup.BackupZipOutput
 import org.koitharu.kotatsu.core.db.MangaDatabase
+import org.koitharu.kotatsu.core.exceptions.BadBackupFormatException
 import org.koitharu.kotatsu.core.prefs.AppSettings
+import org.koitharu.kotatsu.core.util.ext.printStackTraceDebug
 import java.io.File
 import java.io.FileDescriptor
 import java.io.FileInputStream
@@ -88,7 +90,12 @@ class AppBackupAgent : BackupAgent() {
 				input.copyLimitedTo(output, size)
 			}
 		}
-		val backup = BackupZipInput(tempFile)
+		val backup = try {
+			BackupZipInput.from(tempFile)
+		} catch (e: BadBackupFormatException) {
+			tempFile.delete()
+			throw e
+		}
 		try {
 			runBlocking {
 				backup.getEntry(BackupEntry.Name.HISTORY)?.let { repository.restoreHistory(it) }
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/settings/backup/RestoreViewModel.kt b/app/src/main/kotlin/org/koitharu/kotatsu/settings/backup/RestoreViewModel.kt
index d1497f696..9acb88717 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/settings/backup/RestoreViewModel.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/settings/backup/RestoreViewModel.kt
@@ -1,6 +1,8 @@
 package org.koitharu.kotatsu.settings.backup
 
+import android.content.ContentResolver
 import android.content.Context
+import android.net.Uri
 import androidx.lifecycle.SavedStateHandle
 import dagger.hilt.android.lifecycle.HiltViewModel
 import dagger.hilt.android.qualifiers.ApplicationContext
@@ -11,6 +13,8 @@ import org.koitharu.kotatsu.core.backup.BackupEntry
 import org.koitharu.kotatsu.core.backup.BackupRepository
 import org.koitharu.kotatsu.core.backup.BackupZipInput
 import org.koitharu.kotatsu.core.backup.CompositeResult
+import org.koitharu.kotatsu.core.exceptions.BadBackupFormatException
+import org.koitharu.kotatsu.core.exceptions.UnsupportedFileException
 import org.koitharu.kotatsu.core.ui.BaseViewModel
 import org.koitharu.kotatsu.core.util.ext.MutableEventFlow
 import org.koitharu.kotatsu.core.util.ext.call
@@ -41,7 +45,7 @@ class RestoreViewModel @Inject constructor(
 					input.copyTo(output)
 				}
 			}
-			BackupZipInput(tempFile)
+			BackupZipInput.from(tempFile)
 		}
 	}
 
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 6970d4c88..d914c5561 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -641,4 +641,5 @@
 	<string name="show_pages_thumbs">Show pages thumbnails</string>
 	<string name="show_pages_thumbs_summary">Enable the \"Pages\" tab on the details screen</string>
 	<string name="error_no_data_received">No data was received from server</string>
+	<string name="unsupported_backup_message">Please select a proper Kotatsu backup file</string>
 </resources>