diff --git a/app/src/main/java/app/revanced/manager/patcher/Aligning.kt b/app/src/main/java/app/revanced/manager/patcher/Aligning.kt
index 56d4b70..d8a672d 100644
--- a/app/src/main/java/app/revanced/manager/patcher/Aligning.kt
+++ b/app/src/main/java/app/revanced/manager/patcher/Aligning.kt
@@ -30,7 +30,7 @@ object Aligning {
             }
 
             file.copyEntriesFromFileAligned(
-                ZipFile(inputFile),
+                ZipFile(inputFile, readonly = true),
                 ZipAligner::getEntryAlignment
             )
         }
diff --git a/app/src/main/java/app/revanced/manager/patcher/alignment/zip/ZipFile.kt b/app/src/main/java/app/revanced/manager/patcher/alignment/zip/ZipFile.kt
index faacdaf..a49ffed 100644
--- a/app/src/main/java/app/revanced/manager/patcher/alignment/zip/ZipFile.kt
+++ b/app/src/main/java/app/revanced/manager/patcher/alignment/zip/ZipFile.kt
@@ -5,16 +5,17 @@ import app.revanced.manager.patcher.alignment.zip.structures.ZipEntry
 
 import java.io.Closeable
 import java.io.File
+import java.io.IOException
 import java.io.RandomAccessFile
 import java.nio.ByteBuffer
 import java.nio.channels.FileChannel
 import java.util.zip.CRC32
 import java.util.zip.Deflater
 
-class ZipFile(file: File) : Closeable {
+class ZipFile(file: File, private val readonly: Boolean = false) : Closeable {
     var entries: MutableList<ZipEntry> = mutableListOf()
 
-    private val filePointer: RandomAccessFile = RandomAccessFile(file, "rw")
+    private val filePointer: RandomAccessFile = RandomAccessFile(file, if (readonly) "r" else "rw")
     private var CDNeedsRewrite = false
 
     private val compressionLevel = 5
@@ -34,6 +35,10 @@ class ZipFile(file: File) : Closeable {
         filePointer.seek(0)
     }
 
+    private fun assertWritable() {
+        if (readonly) throw IOException("Archive is read-only")
+    }
+
     private fun findEndRecord(): ZipEndRecord {
         //look from end to start since end record is at the end
         for (i in filePointer.length() - 1 downTo 0) {
@@ -110,6 +115,8 @@ class ZipFile(file: File) : Closeable {
     }
 
     fun addEntryCompressData(entry: ZipEntry, data: ByteArray) {
+        assertWritable()
+
         val compressor = Deflater(compressionLevel, true)
         compressor.setInput(data)
         compressor.finish()
@@ -136,6 +143,8 @@ class ZipFile(file: File) : Closeable {
     }
 
     private fun addEntryCopyData(entry: ZipEntry, data: ByteBuffer, alignment: Int? = null) {
+        assertWritable()
+
         alignment?.let {
             //calculate where data would end up
             val dataOffset = filePointer.filePointer + entry.LFHSize
@@ -162,6 +171,8 @@ class ZipFile(file: File) : Closeable {
     }
 
     fun copyEntriesFromFileAligned(file: ZipFile, entryAlignment: (entry: ZipEntry) -> Int?) {
+        assertWritable()
+
         for (entry in file.entries) {
             if (entries.any { it.fileName == entry.fileName }) continue //don't add duplicates