diff --git a/asm/src/main/java/dev/openrs2/asm/classpath/AsmClassMetadata.kt b/asm/src/main/java/dev/openrs2/asm/classpath/AsmClassMetadata.kt
index e4e72fd0..9c1af044 100644
--- a/asm/src/main/java/dev/openrs2/asm/classpath/AsmClassMetadata.kt
+++ b/asm/src/main/java/dev/openrs2/asm/classpath/AsmClassMetadata.kt
@@ -16,10 +16,10 @@ class AsmClassMetadata(
         get() = clazz.access and Opcodes.ACC_INTERFACE != 0
 
     override val superClass
-        get() = if (clazz.superName != null) classPath[clazz.superName] else null
+        get() = if (clazz.superName != null) classPath[clazz.superName]!! else null
 
     override val superInterfaces
-        get() = clazz.interfaces.map { classPath[it] }.toList()
+        get() = clazz.interfaces.map { classPath[it]!! }.toList()
 
     override val fields
         get() = clazz.fields.map { MemberDesc(it) }.toList()
diff --git a/asm/src/main/java/dev/openrs2/asm/classpath/ClassPath.kt b/asm/src/main/java/dev/openrs2/asm/classpath/ClassPath.kt
index 58028e5e..9a496535 100644
--- a/asm/src/main/java/dev/openrs2/asm/classpath/ClassPath.kt
+++ b/asm/src/main/java/dev/openrs2/asm/classpath/ClassPath.kt
@@ -13,20 +13,30 @@ class ClassPath(
     private val dependencies: List<Library>,
     val libraries: List<Library>
 ) {
-    private val cache = mutableMapOf<String, ClassMetadata>()
+    private val cache = mutableMapOf<String, ClassMetadata?>()
 
     val libraryClasses: List<ClassMetadata>
         get() {
             val classes = mutableListOf<ClassMetadata>()
             for (library in libraries) {
                 for (clazz in library) {
-                    classes.add(get(clazz.name))
+                    classes.add(get(clazz.name)!!)
                 }
             }
             return classes
         }
 
-    operator fun get(name: String): ClassMetadata = cache.computeIfAbsent(name) {
+    private inline fun computeIfAbsent(name: String, f: (String) -> ClassMetadata?): ClassMetadata? {
+        if (cache.containsKey(name)) {
+            return cache[name]
+        }
+
+        val clazz = f(name)
+        cache[name] = clazz
+        return clazz
+    }
+
+    operator fun get(name: String): ClassMetadata? = computeIfAbsent(name) {
         for (library in libraries) {
             val clazz = library[name]
             if (clazz != null) {
@@ -44,7 +54,7 @@ class ClassPath(
         val clazz = try {
             runtime.loadClass(name.toBinaryClassName())
         } catch (ex: ClassNotFoundException) {
-            throw IllegalArgumentException("Unknown class $name")
+            return@computeIfAbsent null
         }
 
         return@computeIfAbsent ReflectionClassMetadata(this, clazz)
@@ -75,7 +85,7 @@ class ClassPath(
 
         for (library in libraries) {
             for (clazz in library) {
-                populateInheritedFieldSets(ancestorCache, disjointSet, get(clazz.name))
+                populateInheritedFieldSets(ancestorCache, disjointSet, get(clazz.name)!!)
             }
         }
 
@@ -130,7 +140,7 @@ class ClassPath(
 
         for (library in libraries) {
             for (clazz in library) {
-                populateInheritedMethodSets(ancestorCache, disjointSet, get(clazz.name))
+                populateInheritedMethodSets(ancestorCache, disjointSet, get(clazz.name)!!)
             }
         }
 
diff --git a/asm/src/main/java/dev/openrs2/asm/classpath/ReflectionClassMetadata.kt b/asm/src/main/java/dev/openrs2/asm/classpath/ReflectionClassMetadata.kt
index d39ad244..74fa9337 100644
--- a/asm/src/main/java/dev/openrs2/asm/classpath/ReflectionClassMetadata.kt
+++ b/asm/src/main/java/dev/openrs2/asm/classpath/ReflectionClassMetadata.kt
@@ -18,10 +18,10 @@ class ReflectionClassMetadata(private val classPath: ClassPath, private val claz
         get() = clazz.isInterface
 
     override val superClass: ClassMetadata?
-        get() = if (clazz.superclass != null) classPath[clazz.superclass.asmName] else null
+        get() = if (clazz.superclass != null) classPath[clazz.superclass.asmName]!! else null
 
     override val superInterfaces
-        get() = clazz.interfaces.map { classPath[it.asmName] }.toList()
+        get() = clazz.interfaces.map { classPath[it.asmName]!! }.toList()
 
     override val fields
         get() = clazz.declaredFields.map { MemberDesc(it.name, Type.getDescriptor(it.type)) }.toList()
diff --git a/deob/src/main/java/dev/openrs2/deob/remap/TypedRemapper.kt b/deob/src/main/java/dev/openrs2/deob/remap/TypedRemapper.kt
index 19f6ec14..5e4e1025 100644
--- a/deob/src/main/java/dev/openrs2/deob/remap/TypedRemapper.kt
+++ b/deob/src/main/java/dev/openrs2/deob/remap/TypedRemapper.kt
@@ -137,7 +137,7 @@ class TypedRemapper private constructor(
                 var skip = false
 
                 for ((owner, name) in partition) {
-                    val clazz = classPath[owner]
+                    val clazz = classPath[owner]!!
 
                     if (name in EXCLUDED_FIELDS) {
                         skip = true
@@ -187,7 +187,7 @@ class TypedRemapper private constructor(
 
         fun isMethodImmutable(classPath: ClassPath, partition: DisjointSet.Partition<MemberRef>): Boolean {
             for (method in partition) {
-                val clazz = classPath[method.owner]
+                val clazz = classPath[method.owner]!!
 
                 if (method.name in EXCLUDED_METHODS) {
                     return true
diff --git a/deob/src/main/java/dev/openrs2/deob/transform/OverrideTransformer.kt b/deob/src/main/java/dev/openrs2/deob/transform/OverrideTransformer.kt
index 4717da43..8780341e 100644
--- a/deob/src/main/java/dev/openrs2/deob/transform/OverrideTransformer.kt
+++ b/deob/src/main/java/dev/openrs2/deob/transform/OverrideTransformer.kt
@@ -28,7 +28,7 @@ class OverrideTransformer : Transformer() {
             return false
         }
 
-        if (!classPath[clazz.name].isOverride(MemberDesc(method))) {
+        if (!classPath[clazz.name]!!.isOverride(MemberDesc(method))) {
             return false
         }