diff --git a/usr.sbin/makefs/ffs/mkfs.c b/usr.sbin/makefs/ffs/mkfs.c
index 0c8447150f0e..e885d23613bb 100644
--- a/usr.sbin/makefs/ffs/mkfs.c
+++ b/usr.sbin/makefs/ffs/mkfs.c
@@ -408,6 +408,7 @@ ffs_mkfs(const char *fsys, const fsinfo_t *fsopts, time_t tstamp)
 	if (sblock.fs_contigsumsize > 0)
 		size += sblock.fs_ncg * sizeof(int32_t);
 	space = ecalloc(1, size);
+	sblock.fs_si = ecalloc(1, sizeof(struct fs_summary_info));
 	sblock.fs_csp = space;
 	space = (char *)space + sblock.fs_cssize;
 	if (sblock.fs_contigsumsize > 0) {