diff --git a/asm/src/main/java/dev/openrs2/asm/classpath/Library.kt b/asm/src/main/java/dev/openrs2/asm/classpath/Library.kt
index fab26bdd..88429dba 100644
--- a/asm/src/main/java/dev/openrs2/asm/classpath/Library.kt
+++ b/asm/src/main/java/dev/openrs2/asm/classpath/Library.kt
@@ -22,6 +22,7 @@ import java.util.TreeMap
 import java.util.jar.JarEntry
 import java.util.jar.JarInputStream
 import java.util.jar.JarOutputStream
+import java.util.jar.Manifest
 import java.util.zip.GZIPInputStream
 import java.util.zip.GZIPOutputStream
 
@@ -79,14 +80,16 @@ class Library constructor() : Iterable<ClassNode> {
         }
     }
 
-    fun writeJar(path: Path) {
+    fun writeJar(path: Path, manifest: Manifest? = null) {
         logger.info { "Writing jar $path" }
 
-        Files.newOutputStream(path).use(::writeJar)
+        Files.newOutputStream(path).use {
+            writeJar(it, manifest)
+        }
     }
 
-    fun writeJar(out: OutputStream) {
-        DeterministicJarOutputStream(out).use { jar ->
+    fun writeJar(out: OutputStream, manifest: Manifest? = null) {
+        DeterministicJarOutputStream.create(out, manifest).use { jar ->
             for (clazz in classes.values) {
                 val writer = ClassWriter(0)
 
diff --git a/common/src/main/java/dev/openrs2/common/io/DeterministicJarOutputStream.kt b/common/src/main/java/dev/openrs2/common/io/DeterministicJarOutputStream.kt
index 9a65fc1c..fd19642d 100644
--- a/common/src/main/java/dev/openrs2/common/io/DeterministicJarOutputStream.kt
+++ b/common/src/main/java/dev/openrs2/common/io/DeterministicJarOutputStream.kt
@@ -7,8 +7,8 @@ import java.util.jar.Manifest
 import java.util.zip.ZipEntry
 
 class DeterministicJarOutputStream : JarOutputStream {
-    constructor(out: OutputStream) : super(out)
-    constructor(out: OutputStream, man: Manifest) : super(out, man)
+    private constructor(out: OutputStream) : super(out)
+    private constructor(out: OutputStream, man: Manifest) : super(out, man)
 
     override fun putNextEntry(ze: ZipEntry) {
         ze.creationTime = UNIX_EPOCH
@@ -19,5 +19,13 @@ class DeterministicJarOutputStream : JarOutputStream {
 
     companion object {
         private val UNIX_EPOCH = FileTime.fromMillis(0)
+
+        fun create(out: OutputStream, manifest: Manifest? = null): JarOutputStream {
+            return if (manifest != null) {
+                DeterministicJarOutputStream(out, manifest)
+            } else {
+                DeterministicJarOutputStream(out)
+            }
+        }
     }
 }