diff --git a/src/main/java/dan200/computercraft/shared/computer/upload/UploadResult.java b/src/main/java/dan200/computercraft/shared/computer/upload/UploadResult.java
index d785080cd..ed480b609 100644
--- a/src/main/java/dan200/computercraft/shared/computer/upload/UploadResult.java
+++ b/src/main/java/dan200/computercraft/shared/computer/upload/UploadResult.java
@@ -14,8 +14,6 @@ public enum UploadResult
     CONSUMED,
     ERROR;
 
-    public static final ITextComponent SUCCESS_TITLE = new TranslationTextComponent( "gui.computercraft.upload.success" );
-
     public static final ITextComponent FAILED_TITLE = new TranslationTextComponent( "gui.computercraft.upload.failed" );
     public static final ITextComponent COMPUTER_OFF_MSG = new TranslationTextComponent( "gui.computercraft.upload.failed.computer_off" );
     public static final ITextComponent TOO_MUCH_MSG = new TranslationTextComponent( "gui.computercraft.upload.failed.too_much" );
diff --git a/src/main/resources/assets/computercraft/lang/en_us.json b/src/main/resources/assets/computercraft/lang/en_us.json
index 33de587af..4f6f730e5 100644
--- a/src/main/resources/assets/computercraft/lang/en_us.json
+++ b/src/main/resources/assets/computercraft/lang/en_us.json
@@ -116,8 +116,6 @@
     "gui.computercraft.tooltip.turn_off.key": "Hold Ctrl+S",
     "gui.computercraft.tooltip.terminate": "Stop the currently running code",
     "gui.computercraft.tooltip.terminate.key": "Hold Ctrl+T",
-    "gui.computercraft.upload.success": "Upload Succeeded",
-    "gui.computercraft.upload.success.msg": "%d files uploaded.",
     "gui.computercraft.upload.failed": "Upload Failed",
     "gui.computercraft.upload.failed.computer_off": "You must turn the computer on before uploading files.",
     "gui.computercraft.upload.failed.too_much": "Your files are too large to be uploaded.",
diff --git a/src/testFixtures/kotlin/dan200/computercraft/test/core/computer/KotlinLuaMachine.kt b/src/testFixtures/kotlin/dan200/computercraft/test/core/computer/KotlinLuaMachine.kt
index ad36ae258..3e94dea31 100644
--- a/src/testFixtures/kotlin/dan200/computercraft/test/core/computer/KotlinLuaMachine.kt
+++ b/src/testFixtures/kotlin/dan200/computercraft/test/core/computer/KotlinLuaMachine.kt
@@ -5,11 +5,9 @@ import dan200.computercraft.api.lua.ILuaContext
 import dan200.computercraft.core.lua.ILuaMachine
 import dan200.computercraft.core.lua.MachineEnvironment
 import dan200.computercraft.core.lua.MachineResult
-import kotlinx.coroutines.CoroutineName
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.launch
+import kotlinx.coroutines.*
 import java.io.InputStream
+import kotlin.coroutines.CoroutineContext
 
 /**
  * An [ILuaMachine] which runs Kotlin functions instead.
@@ -26,7 +24,7 @@ abstract class KotlinLuaMachine(environment: MachineEnvironment) : ILuaMachine,
             queueEvent(eventName, arguments)
         } else {
             val task = getTask()
-            if (task != null) CoroutineScope(Dispatchers.Unconfined + CoroutineName("Computer")).launch { task() }
+            if (task != null) CoroutineScope(NeverDispatcher() + CoroutineName("Computer")).launch { task() }
         }
 
         return MachineResult.OK
@@ -38,4 +36,20 @@ abstract class KotlinLuaMachine(environment: MachineEnvironment) : ILuaMachine,
      * Get the next task to execute on this computer.
      */
     protected abstract fun getTask(): (suspend KotlinLuaMachine.() -> Unit)?
+
+    /**
+     * A [CoroutineDispatcher] which only allows resuming from the computer thread. In practice, this means the only
+     * way to yield is with [pullEvent].
+     */
+    private class NeverDispatcher : CoroutineDispatcher() {
+        private val expectedGroup = Thread.currentThread().threadGroup
+
+        override fun dispatch(context: CoroutineContext, block: Runnable) {
+            if (Thread.currentThread().threadGroup != expectedGroup) {
+                throw UnsupportedOperationException("Cannot perform arbitrary yields")
+            }
+
+            block.run()
+        }
+    }
 }
diff --git a/src/testFixtures/kotlin/dan200/computercraft/test/core/computer/LuaTaskContext.kt b/src/testFixtures/kotlin/dan200/computercraft/test/core/computer/LuaTaskContext.kt
index 28ab11c3a..066045b87 100644
--- a/src/testFixtures/kotlin/dan200/computercraft/test/core/computer/LuaTaskContext.kt
+++ b/src/testFixtures/kotlin/dan200/computercraft/test/core/computer/LuaTaskContext.kt
@@ -4,9 +4,11 @@ import dan200.computercraft.api.lua.ILuaAPI
 import dan200.computercraft.api.lua.ILuaContext
 import dan200.computercraft.api.lua.MethodResult
 import dan200.computercraft.api.lua.ObjectArguments
+import dan200.computercraft.core.apis.OSAPI
 import dan200.computercraft.core.apis.PeripheralAPI
 import kotlinx.coroutines.CancellableContinuation
 import kotlinx.coroutines.suspendCancellableCoroutine
+import kotlin.time.Duration
 
 /**
  * The context for tasks which consume Lua objects.
@@ -40,6 +42,19 @@ interface LuaTaskContext {
     /** Call a peripheral method. */
     suspend fun LuaTaskContext.callPeripheral(name: String, method: String, vararg args: Any?): Array<out Any?>? =
         getApi<PeripheralAPI>().call(context, ObjectArguments(name, method, *args)).await()
+
+    /**
+     * Sleep for the given duration. This uses the internal computer clock, so won't be accurate.
+     */
+    suspend fun LuaTaskContext.sleep(duration: Duration) {
+        val timer = getApi<OSAPI>().startTimer(duration.inWholeMilliseconds / 1000.0)
+        while (true) {
+            val event = pullEvent("timer")
+            if (event[0] == "timer" && event[1] is Number && (event[1] as Number).toInt() == timer) {
+                return
+            }
+        }
+    }
 }
 
 /** Get a registered API. */