diff --git a/freelist/freelist.c b/freelist/freelist.c
index f9dc531..380010f 100644
--- a/freelist/freelist.c
+++ b/freelist/freelist.c
@@ -6,10 +6,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-struct FreeListBlock {
-    struct FreeListBlock *next;
-};
-
 /* Initialize the FreeList */
 int fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize) {
     size_t size = ALIGN(itemsize);
diff --git a/freelist/freelist.h b/freelist/freelist.h
index f0cf7c7..f0e8ed4 100644
--- a/freelist/freelist.h
+++ b/freelist/freelist.h
@@ -18,14 +18,19 @@ static inline size_t align_up(size_t n) {
 #define ALIGN(x) (align_up(x))
 #endif // FREELIST_NOALIGN
 
-typedef struct FreeListBlock FreeListBlock;
+#define FL_FREE ((uint8_t)0x00)
+#define FL_USED ((uint8_t)0x01)
+
+typedef struct FreeListBlock {
+    struct FreeListBlock *next;
+} FreeListBlock;
 
 typedef struct {
-    uintptr_t  start;
-    uintptr_t  end;
+    uintptr_t      start;
+    uintptr_t      end;
     FreeListBlock *free;
-    size_t     size;
-    size_t     allocated;
+    size_t         size;
+    size_t         allocated;
 } FreeList;
 
 int    fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize);