diff --git a/src/module/io.c b/src/module/io.c
index 3300ec40..2355d14c 100644
--- a/src/module/io.c
+++ b/src/module/io.c
@@ -107,33 +107,18 @@ static void directoryListCallback(uv_fs_t* request)
 
   uv_dirent_t entry;
 
-  // TODO: Right now, there's no way to create a list using the C API, so
-  // create a buffer containing all of the result paths terminated by '\0'.
-  // We'll split that back into a list in Wren.
-  size_t bufferLength = 0;
-  size_t bufferCapacity = 1024;
-  char* buffer = (char*)malloc(bufferCapacity);
+  WrenVM* vm = getVM();
+  wrenEnsureSlots(vm, 3);
+  wrenSetSlotNewList(vm, 2);
   
   while (uv_fs_scandir_next(request, &entry) != UV_EOF)
   {
-    size_t length = strlen(entry.name);
-    
-    // Grow the buffer if needed.
-    while (bufferLength + length + 1 > bufferCapacity)
-    {
-      bufferCapacity *= 2;
-      buffer = (char*)realloc(buffer, bufferCapacity);
-    }
-    
-    // Copy the path, including the null terminator.
-    memcpy(buffer + bufferLength, entry.name, length + 1);
-    bufferLength += length + 1;
+    wrenSetSlotString(vm, 1, entry.name);
+    wrenInsertInList(vm, 2, -1, 1);
   }
   
   schedulerResume(freeRequest(request), true);
-  wrenSetSlotBytes(getVM(), 2, buffer, bufferLength);
   schedulerFinishResume();
-  free(buffer);
 }
 
 void directoryList(WrenVM* vm)
diff --git a/src/module/io.wren b/src/module/io.wren
index d641743a..9694d2f9 100644
--- a/src/module/io.wren
+++ b/src/module/io.wren
@@ -5,28 +5,7 @@ class Directory {
     if (!(path is String)) Fiber.abort("Path must be a string.")
 
     list_(path, Fiber.current)
-
-    // We get back a byte array containing all of the paths, each terminated by
-    // a zero byte.
-    var entryBuffer = Scheduler.runNextScheduled_()
-
-    // TODO: Add split() to String.
-    // Split it into an array of strings.
-    var entries = []
-    var start = 0
-    var i = 0
-    var bytes = entryBuffer.bytes
-    while (i < bytes.count) {
-      if (bytes[i] == 0) {
-        var entry = entryBuffer[start...i]
-        start = i + 1
-        entries.add(entry)
-      }
-
-      i = i + 1
-    }
-
-    return entries
+    return Scheduler.runNextScheduled_()
   }
 
   foreign static list_(path, fiber)
diff --git a/src/module/io.wren.inc b/src/module/io.wren.inc
index 32b62086..770657c9 100644
--- a/src/module/io.wren.inc
+++ b/src/module/io.wren.inc
@@ -7,28 +7,7 @@ static const char* ioModuleSource =
 "    if (!(path is String)) Fiber.abort(\"Path must be a string.\")\n"
 "\n"
 "    list_(path, Fiber.current)\n"
-"\n"
-"    // We get back a byte array containing all of the paths, each terminated by\n"
-"    // a zero byte.\n"
-"    var entryBuffer = Scheduler.runNextScheduled_()\n"
-"\n"
-"    // TODO: Add split() to String.\n"
-"    // Split it into an array of strings.\n"
-"    var entries = []\n"
-"    var start = 0\n"
-"    var i = 0\n"
-"    var bytes = entryBuffer.bytes\n"
-"    while (i < bytes.count) {\n"
-"      if (bytes[i] == 0) {\n"
-"        var entry = entryBuffer[start...i]\n"
-"        start = i + 1\n"
-"        entries.add(entry)\n"
-"      }\n"
-"\n"
-"      i = i + 1\n"
-"    }\n"
-"\n"
-"    return entries\n"
+"    return Scheduler.runNextScheduled_()\n"
 "  }\n"
 "\n"
 "  foreign static list_(path, fiber)\n"
diff --git a/src/vm/wren_debug.c b/src/vm/wren_debug.c
index 572c826d..2d5d7063 100644
--- a/src/vm/wren_debug.c
+++ b/src/vm/wren_debug.c
@@ -20,6 +20,9 @@ void wrenDebugPrintStackTrace(ObjFiber* fiber)
     CallFrame* frame = &fiber->frames[i];
     ObjFn* fn = wrenUpwrapClosure(frame->fn);
 
+    // Skip over stub functions for calling methods from the C API.
+    if (fn->module == NULL) continue;
+    
     // The built-in core module has no name. We explicitly omit it from stack
     // traces since we don't want to highlight to a user the implementation
     // detail of what part of the core module is written in C and what is Wren.
diff --git a/src/vm/wren_vm.c b/src/vm/wren_vm.c
index f281a62f..2d6f0029 100644
--- a/src/vm/wren_vm.c
+++ b/src/vm/wren_vm.c
@@ -1311,23 +1311,30 @@ WrenInterpretResult wrenCall(WrenVM* vm, WrenValue* method)
   ASSERT(vm->fiber->stackTop - vm->fiber->stack >= fn->arity,
          "Stack must have enough arguments for method.");
   
-  callFunction(vm, vm->fiber, (Obj*)fn, fn->arity);
+  // Discard any extra temporary slots. We take for granted that the stub
+  // function has exactly one slot for each arguments.
+  vm->fiber->stackTop = &vm->fiber->stack[fn->maxSlots];
   
+  callFunction(vm, vm->fiber, (Obj*)fn, 0);
   return runInterpreter(vm, vm->fiber);
 }
 
 WrenValue* wrenCaptureValue(WrenVM* vm, Value value)
 {
+  if (IS_OBJ(value)) wrenPushRoot(vm, AS_OBJ(value));
+  
   // Make a handle for it.
   WrenValue* wrappedValue = ALLOCATE(vm, WrenValue);
   wrappedValue->value = value;
 
+  if (IS_OBJ(value)) wrenPopRoot(vm);
+
   // Add it to the front of the linked list of handles.
   if (vm->valueHandles != NULL) vm->valueHandles->prev = wrappedValue;
   wrappedValue->prev = NULL;
   wrappedValue->next = vm->valueHandles;
   vm->valueHandles = wrappedValue;
-
+  
   return wrappedValue;
 }
 
diff --git a/test/api/call.c b/test/api/call.c
index f7d8af8a..d119dde9 100644
--- a/test/api/call.c
+++ b/test/api/call.c
@@ -73,6 +73,15 @@ void callRunTests(WrenVM* vm)
   wrenSetSlotBytes(vm, 2, "b\0y\0t\0e", 7);
   wrenCall(vm, two);
   
+  // Call ignores with extra temporary slots on stack.
+  wrenEnsureSlots(vm, 10);
+  wrenSetSlotValue(vm, 0, callClass);
+  for (int i = 1; i < 10; i++)
+  {
+    wrenSetSlotDouble(vm, i, i * 0.1);
+  }
+  wrenCall(vm, one);
+  
   wrenReleaseValue(vm, callClass);
   wrenReleaseValue(vm, noParams);
   wrenReleaseValue(vm, zero);
diff --git a/test/api/call.wren b/test/api/call.wren
index 889a7936..afe8e9e3 100644
--- a/test/api/call.wren
+++ b/test/api/call.wren
@@ -33,3 +33,4 @@ class Call {
 // expect: two string another
 // expect: two null [a, b]
 // expect: two str [98, 0, 121, 0, 116, 0, 101]
+// expect: one 0.1