diff --git a/sys/vfs/hammer/hammer_disk.h b/sys/vfs/hammer/hammer_disk.h
index 7de627a..3f956b2 100644
--- a/sys/vfs/hammer/hammer_disk.h
+++ b/sys/vfs/hammer/hammer_disk.h
@@ -819,7 +819,7 @@ struct hammer_pseudofs_data {
 	int32_t		prune_min;	/* do not prune recent history */
 	int32_t		prune_max;	/* do not retain history beyond here */
 	int32_t		reserved[16];
-};
+} __packed;
 
 typedef struct hammer_pseudofs_data *hammer_pseudofs_data_t;
 
diff --git a/sys/vfs/hammer/hammer_ioctl.h b/sys/vfs/hammer/hammer_ioctl.h
index ace6fef..bba8637 100644
--- a/sys/vfs/hammer/hammer_ioctl.h
+++ b/sys/vfs/hammer/hammer_ioctl.h
@@ -294,7 +294,7 @@ struct hammer_ioc_mrecord_head {
 	u_int32_t		rec_size;
 	u_int32_t		type;
 	/* extended */
-};
+} __packed;
 
 typedef struct hammer_ioc_mrecord_head *hammer_ioc_mrecord_head_t;
 
@@ -302,29 +302,29 @@ struct hammer_ioc_mrecord_rec {
 	struct hammer_ioc_mrecord_head	head;
 	struct hammer_btree_leaf_elm	leaf;
 	/* extended by data */
-};
+} __packed;
 
 struct hammer_ioc_mrecord_skip {
 	struct hammer_ioc_mrecord_head	head;
 	struct hammer_base_elm	 	skip_beg;
 	struct hammer_base_elm 		skip_end;
-};
+} __packed;
 
 struct hammer_ioc_mrecord_update {
 	struct hammer_ioc_mrecord_head	head;
 	hammer_tid_t			tid;
-};
+} __packed;
 
 struct hammer_ioc_mrecord_sync {
 	struct hammer_ioc_mrecord_head	head;
-};
+} __packed;
 
 struct hammer_ioc_mrecord_pfs {
 	struct hammer_ioc_mrecord_head	head;
 	u_int32_t			version;
 	u_int32_t			reserved01;
 	struct hammer_pseudofs_data	pfsd;
-};
+} __packed;
 
 struct hammer_ioc_version {
 	struct hammer_ioc_head head;
@@ -351,7 +351,7 @@ union hammer_ioc_mrecord_any {
 	struct hammer_ioc_mrecord_update sync;
 	struct hammer_ioc_mrecord_pfs	pfs;
 	struct hammer_ioc_version	version;
-};
+} __packed;
 
 typedef union hammer_ioc_mrecord_any *hammer_ioc_mrecord_any_t;