diff --git a/encryptedstore/src/main.rs b/encryptedstore/src/main.rs
index 7a41f13..86fa6da 100644
--- a/encryptedstore/src/main.rs
+++ b/encryptedstore/src/main.rs
@@ -125,9 +125,13 @@
 
 fn format_ext4(device: &Path) -> Result<()> {
     let mkfs_options = [
-        "-j",               // Create appropriate sized journal
-        "-O metadata_csum", // Metadata checksum for filesystem integrity
-        "-b 4096",          // block size in the filesystem
+        "-j", // Create appropriate sized journal
+        /* metadata_csum: enabled for filesystem integrity
+         * extents: Not enabling extents reduces the coverage of metadata checksumming.
+         * 64bit: larger fields afforded by this feature enable full-strength checksumming.
+         */
+        "-O metadata_csum, extents, 64bit",
+        "-b 4096", // block size in the filesystem
     ];
     let mut cmd = Command::new(MK2FS_BIN);
     let status = cmd