diff --git a/tool/build.gradle.kts b/tool/build.gradle.kts
index 9174b7c..29bddc7 100644
--- a/tool/build.gradle.kts
+++ b/tool/build.gradle.kts
@@ -10,6 +10,7 @@ dependencies {
   api(project(":compiler"))
   api(project(":vm"))
   api("com.github.ajalt.clikt:clikt:4.2.0")
+  api("com.charleskorn.kaml:kaml:0.55.0")
 
   implementation(project(":common"))
 }
diff --git a/tool/src/main/kotlin/gay/pizza/pork/tool/CompileCommand.kt b/tool/src/main/kotlin/gay/pizza/pork/tool/CompileCommand.kt
index 4689698..1bb892e 100644
--- a/tool/src/main/kotlin/gay/pizza/pork/tool/CompileCommand.kt
+++ b/tool/src/main/kotlin/gay/pizza/pork/tool/CompileCommand.kt
@@ -1,5 +1,7 @@
 package gay.pizza.pork.tool
 
+import com.charleskorn.kaml.PolymorphismStyle
+import com.charleskorn.kaml.Yaml
 import com.github.ajalt.clikt.core.CliktCommand
 import com.github.ajalt.clikt.parameters.arguments.argument
 import gay.pizza.dough.fs.PlatformFsProvider
@@ -8,10 +10,7 @@ import gay.pizza.pork.bir.IrWorld
 import gay.pizza.pork.bytecode.CompiledWorld
 import gay.pizza.pork.compiler.Compiler
 import gay.pizza.pork.minimal.FileTool
-import kotlinx.serialization.ExperimentalSerializationApi
-import kotlinx.serialization.json.Json
 
-@OptIn(ExperimentalSerializationApi::class)
 class CompileCommand : CliktCommand(help = "Compile Pork to Bytecode", name = "compile") {
   val path by argument("file")
 
@@ -30,11 +29,10 @@ class CompileCommand : CliktCommand(help = "Compile Pork to Bytecode", name = "c
   }
 
   private fun printCompiledIr(irWorld: IrWorld) {
-    val json = Json {
-      prettyPrint = true
-      prettyPrintIndent = "  "
-    }
-    println(json.encodeToString(IrWorld.serializer(), irWorld))
+    val yaml = Yaml(configuration = Yaml.default.configuration.copy(
+      polymorphismStyle = PolymorphismStyle.Property
+    ))
+    println(yaml.encodeToString(IrWorld.serializer(), irWorld))
   }
 
   private fun printCompiledWorld(compiledWorld: CompiledWorld) {
diff --git a/vm/src/main/kotlin/gay/pizza/pork/vm/InternalMachine.kt b/vm/src/main/kotlin/gay/pizza/pork/vm/InternalMachine.kt
index 1bf37c0..5fc04f4 100644
--- a/vm/src/main/kotlin/gay/pizza/pork/vm/InternalMachine.kt
+++ b/vm/src/main/kotlin/gay/pizza/pork/vm/InternalMachine.kt
@@ -13,8 +13,8 @@ class InternalMachine(val world: CompiledWorld, val nativeRegistry: NativeRegist
 
   private var inst: UInt = 0u
   private val stack = mutableListOf<Any>()
-  private val locals = mutableListOf<MutableMap<UInt, Any>>(
-    mutableMapOf()
+  private val locals = mutableListOf(
+    LocalSlots()
   )
   private val callStack = mutableListOf(0u)
   private val returnAddressStack = mutableListOf<UInt>()
@@ -32,7 +32,7 @@ class InternalMachine(val world: CompiledWorld, val nativeRegistry: NativeRegist
   }
 
   fun pushScope() {
-    locals.add(mutableMapOf())
+    locals.add(LocalSlots())
   }
 
   fun popScope() {
@@ -43,14 +43,13 @@ class InternalMachine(val world: CompiledWorld, val nativeRegistry: NativeRegist
     val constant = world.constantPool.constants[id.toInt()]
     when (constant.tag) {
       ConstantTag.String -> push(String(constant.value))
-      else -> throw VirtualMachineException("Unknown Constant Tag: ${constant.tag.name}")
+      else -> throw VirtualMachineException("Unknown constant tag: ${constant.tag.name}")
     }
   }
 
   fun localAt(id: UInt): Any {
     val localSet = locals.last()
-    return localSet[id] ?:
-      throw VirtualMachineException("Attempted to load local $id but it was not stored.")
+    return localSet.load(id)
   }
 
   fun loadLocal(id: UInt) {
@@ -60,7 +59,7 @@ class InternalMachine(val world: CompiledWorld, val nativeRegistry: NativeRegist
   fun storeLocal(id: UInt) {
     val localSet = locals.last()
     val value = popAnyValue()
-    localSet[id] = value
+    localSet.store(id, value)
   }
 
   fun setNextInst(value: UInt) {
@@ -106,7 +105,7 @@ class InternalMachine(val world: CompiledWorld, val nativeRegistry: NativeRegist
     callStack.clear()
     callStack.add(0u)
     locals.clear()
-    locals.add(mutableMapOf())
+    locals.add(LocalSlots())
     inst = 0u
     exitFlag = false
     autoNextInst = true
diff --git a/vm/src/main/kotlin/gay/pizza/pork/vm/LocalSlots.kt b/vm/src/main/kotlin/gay/pizza/pork/vm/LocalSlots.kt
new file mode 100644
index 0000000..6fe0dfd
--- /dev/null
+++ b/vm/src/main/kotlin/gay/pizza/pork/vm/LocalSlots.kt
@@ -0,0 +1,25 @@
+package gay.pizza.pork.vm
+
+class LocalSlots {
+  private var slots = arrayOfNulls<Any>(4)
+
+  fun load(index: UInt): Any {
+    return slots[index.toInt()]
+      ?: throw VirtualMachineException("Attempted to access local $index that is not stored")
+  }
+
+  fun store(index: UInt, value: Any) {
+    if (index >= slots.size.toUInt()) {
+      resize(index + 4u)
+    }
+    slots[index.toInt()] = value
+  }
+
+  private fun resize(count: UInt) {
+    val values = arrayOfNulls<Any>(count.toInt())
+    for ((i, value) in slots.withIndex()) {
+      values[i] = value
+    }
+    slots = values
+  }
+}
diff --git a/vm/src/main/kotlin/gay/pizza/pork/vm/ops/AndOpHandler.kt b/vm/src/main/kotlin/gay/pizza/pork/vm/ops/AndOpHandler.kt
index afc1e01..07c34c3 100644
--- a/vm/src/main/kotlin/gay/pizza/pork/vm/ops/AndOpHandler.kt
+++ b/vm/src/main/kotlin/gay/pizza/pork/vm/ops/AndOpHandler.kt
@@ -7,8 +7,8 @@ import gay.pizza.pork.vm.OpHandler
 
 object AndOpHandler : OpHandler(Opcode.And) {
   override fun handle(machine: InternalMachine, op: Op) {
-    val left = machine.pop<Boolean>()
     val right = machine.pop<Boolean>()
+    val left = machine.pop<Boolean>()
     machine.push(left && right)
   }
 }
diff --git a/vm/src/main/kotlin/gay/pizza/pork/vm/ops/MultiplyOpHandler.kt b/vm/src/main/kotlin/gay/pizza/pork/vm/ops/MultiplyOpHandler.kt
index e44ee98..b4c5bf2 100644
--- a/vm/src/main/kotlin/gay/pizza/pork/vm/ops/MultiplyOpHandler.kt
+++ b/vm/src/main/kotlin/gay/pizza/pork/vm/ops/MultiplyOpHandler.kt
@@ -7,8 +7,8 @@ import gay.pizza.pork.vm.OpHandler
 
 object MultiplyOpHandler : OpHandler(Opcode.Multiply) {
   override fun handle(machine: InternalMachine, op: Op) {
-    val left = machine.pop<Int>()
     val right = machine.pop<Int>()
+    val left = machine.pop<Int>()
     machine.push(left * right)
   }
 }
diff --git a/vm/src/main/kotlin/gay/pizza/pork/vm/ops/OrOpHandler.kt b/vm/src/main/kotlin/gay/pizza/pork/vm/ops/OrOpHandler.kt
index 48c348e..9ac2fc5 100644
--- a/vm/src/main/kotlin/gay/pizza/pork/vm/ops/OrOpHandler.kt
+++ b/vm/src/main/kotlin/gay/pizza/pork/vm/ops/OrOpHandler.kt
@@ -7,8 +7,8 @@ import gay.pizza.pork.vm.OpHandler
 
 object OrOpHandler : OpHandler(Opcode.Or) {
   override fun handle(machine: InternalMachine, op: Op) {
-    val left = machine.pop<Boolean>()
     val right = machine.pop<Boolean>()
+    val left = machine.pop<Boolean>()
     machine.push(left || right)
   }
 }