diff --git a/tasks/mm0/include/vm_area.h b/tasks/mm0/include/vm_area.h
index d42014f..4e7b8cc 100644
--- a/tasks/mm0/include/vm_area.h
+++ b/tasks/mm0/include/vm_area.h
@@ -32,7 +32,7 @@
 
 /* Defines the type of file. A device file? Regular file? One used at boot? */
 enum VM_FILE_TYPE {
-	VM_FILE_DEVZERO = 0,
+	VM_FILE_DEVZERO = 1,
 	VM_FILE_REGULAR,
 	VM_FILE_BOOTFILE,
 };
diff --git a/tasks/mm0/src/mmap.c b/tasks/mm0/src/mmap.c
index 49a1ce8..ce8abf0 100644
--- a/tasks/mm0/src/mmap.c
+++ b/tasks/mm0/src/mmap.c
@@ -461,7 +461,7 @@ int do_mmap(struct vm_file *mapfile, unsigned long file_offset, struct tcb *task
 	/* Set up devzero if none given */
 	if (!mapfile) {
 	       if (flags & VMA_ANONYMOUS) {
-			mapfile = get_devzero();
+			BUG_ON(!(mapfile = get_devzero()));
 			file_offset = 0;
 	       } else
 			BUG();
diff --git a/tasks/mm0/src/pagers.c b/tasks/mm0/src/pagers.c
index 57ae5a8..d9b52b7 100644
--- a/tasks/mm0/src/pagers.c
+++ b/tasks/mm0/src/pagers.c
@@ -266,7 +266,7 @@ struct vm_file *get_devzero(void)
 	struct vm_file *f;
 
 	list_for_each_entry(f, &vm_file_list, list)
-		if (f->type & VM_FILE_DEVZERO)
+		if ((f->type & VM_FILE_DEVZERO) == VM_FILE_DEVZERO)
 			return f;
 	return 0;
 }
diff --git a/tasks/mm0/src/task.c b/tasks/mm0/src/task.c
index 84c727f..eb68cac 100644
--- a/tasks/mm0/src/task.c
+++ b/tasks/mm0/src/task.c
@@ -265,7 +265,7 @@ int start_boot_task(struct vm_file *file, struct task_ids *ids)
 
 	/* mmap each task's environment as anonymous memory. */
 	if ((err = do_mmap(0, 0, task, task->env_start,
-			   VM_READ | VM_WRITE | VMA_PRIVATE,
+			   VM_READ | VM_WRITE | VMA_PRIVATE | VMA_ANONYMOUS,
 			   __pfn(task->env_end - task->env_start)) < 0)) {
 		printf("do_mmap: Mapping environment failed with %d.\n",
 		       err);
@@ -274,7 +274,7 @@ int start_boot_task(struct vm_file *file, struct task_ids *ids)
 
 	/* mmap each task's stack as anonymous memory. */
 	if ((err = do_mmap(0, 0, task, task->stack_start,
-			   VM_READ | VM_WRITE | VMA_PRIVATE,
+			   VM_READ | VM_WRITE | VMA_PRIVATE | VMA_ANONYMOUS,
 			   __pfn(task->stack_end - task->stack_start)) < 0)) {
 		printf("do_mmap: Mapping stack failed with %d.\n", err);
 		goto error;
@@ -284,7 +284,7 @@ int start_boot_task(struct vm_file *file, struct task_ids *ids)
 	printf("%s: Mapping utcb for new task at: 0x%x\n", __TASKNAME__,
 	       task->utcb_address);
 	if ((err = do_mmap(0, 0, task, task->utcb_address,
-			   VM_READ | VM_WRITE | VMA_SHARED,
+			   VM_READ | VM_WRITE | VMA_SHARED | VMA_ANONYMOUS,
 			   DEFAULT_UTCB_SIZE) < 0)) {
 		printf("do_mmap: Mapping utcb failed with %d.\n", err);
 		goto error;