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 2fb5d281..9aee6005 100644
--- a/asm/src/main/java/dev/openrs2/asm/classpath/Library.kt
+++ b/asm/src/main/java/dev/openrs2/asm/classpath/Library.kt
@@ -5,8 +5,9 @@ import org.objectweb.asm.commons.Remapper
 import org.objectweb.asm.tree.ClassNode
 import java.util.TreeMap
 
-class Library() : Iterable<ClassNode> {
-    private var classes = TreeMap<String, ClassNode>()
+class Library(classes: Map<String, ClassNode> = emptyMap()) : Iterable<ClassNode> {
+
+    private var classes = TreeMap(classes)
 
     constructor(library: Library) : this() {
         for (clazz in library.classes.values) {
diff --git a/asm/src/main/java/dev/openrs2/asm/io/JarLibraryReader.kt b/asm/src/main/java/dev/openrs2/asm/io/JarLibraryReader.kt
index a9754db4..65b8d71a 100644
--- a/asm/src/main/java/dev/openrs2/asm/io/JarLibraryReader.kt
+++ b/asm/src/main/java/dev/openrs2/asm/io/JarLibraryReader.kt
@@ -4,27 +4,29 @@ import dev.openrs2.asm.classpath.JsrInliner
 import dev.openrs2.asm.classpath.Library
 import org.objectweb.asm.ClassReader
 import org.objectweb.asm.tree.ClassNode
+import java.util.jar.JarEntry
 import java.util.jar.JarInputStream
 
 class JarLibraryReader(private val input: JarInputStream) : LibraryReader {
 
     override fun read(): Library {
-        val library = Library()
+        val classes = generateSequence { input.nextJarEntry }
+            .filter(::isClass)
+            .map { input.readClass() }
+            .associateBy(ClassNode::name)
 
-        while (true) {
-            val entry = input.nextJarEntry ?: break
-            if (!entry.name.endsWith(CLASS_SUFFIX)) {
-                continue
-            }
-
-            val clazz = ClassNode()
-            val reader = ClassReader(input)
-            reader.accept(JsrInliner(clazz), ClassReader.SKIP_DEBUG or ClassReader.SKIP_FRAMES)
+        return Library(classes)
+    }
 
-            library.add(clazz)
-        }
+    private fun isClass(entry: JarEntry): Boolean {
+        return entry.name.endsWith(CLASS_SUFFIX)
+    }
 
-        return library
+    private fun JarInputStream.readClass(): ClassNode {
+        val clazz = ClassNode()
+        val reader = ClassReader(this)
+        reader.accept(JsrInliner(clazz), ClassReader.SKIP_DEBUG or ClassReader.SKIP_FRAMES)
+        return clazz
     }
 
     private companion object {