diff --git a/kernel/include/cls.h b/kernel/include/cls.h
index d778407c..909c4db6 100644
--- a/kernel/include/cls.h
+++ b/kernel/include/cls.h
@@ -21,7 +21,7 @@
 
 struct kmalloc_header {
 	unsigned int front_magic;
-	unsigned int cpu_id;
+	int cpu_id;
 	struct list_head list;
 	int size; /* The size of this chunk without the header */
 	unsigned int end_magic;