diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 4c51aec81f..c7f0184c1b 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -49,6 +49,7 @@ struct thread_local {
 	int pack_fd;
 };
 
+/* Remember to update object flag allocation in object.h */
 #define FLAG_LINK (1u<<20)
 #define FLAG_CHECKED (1u<<21)
 
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 6b9cfc289d..9c3e69e063 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -2546,6 +2546,7 @@ static void read_object_list_from_stdin(void)
 	}
 }
 
+/* Remember to update object flag allocation in object.h */
 #define OBJECT_ADDED (1u<<20)
 
 static void show_commit(struct commit *commit, void *data)
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 2233725315..95becf0e7e 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -52,6 +52,7 @@ struct collect_reflog_cb {
 	int nr;
 };
 
+/* Remember to update object flag allocation in object.h */
 #define INCOMPLETE	(1u<<10)
 #define STUDYING	(1u<<11)
 #define REACHABLE	(1u<<12)
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 62ea264c46..b2ad6fba2f 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -158,6 +158,7 @@ struct obj_info {
 	struct object *obj;
 };
 
+/* Remember to update object flag allocation in object.h */
 #define FLAG_OPEN (1u<<20)
 #define FLAG_WRITTEN (1u<<21)
 
diff --git a/object.h b/object.h
index 87563d9056..15901d2901 100644
--- a/object.h
+++ b/object.h
@@ -29,7 +29,7 @@ struct object_array {
 /*
  * object flag allocation:
  * revision.h:      0---------10                                26
- * fetch-pack.c:    0---5
+ * fetch-pack.c:    0----5
  * walker.c:        0-2
  * upload-pack.c:       4       11----------------19
  * builtin/blame.c:               12-13
@@ -40,6 +40,10 @@ struct object_array {
  * sha1_name.c:                                     20
  * list-objects-filter.c:                             21
  * builtin/fsck.c:  0--3
+ * builtin/index-pack.c:                            2021
+ * builtin/pack-objects.c:                          20
+ * builtin/reflog.c:          10--12
+ * builtin/unpack-objects.c:                        2021
  */
 #define FLAG_BITS  27