diff --git a/src/ctap/storage.rs b/src/ctap/storage.rs
index 7fdf50c..6f75461 100644
--- a/src/ctap/storage.rs
+++ b/src/ctap/storage.rs
@@ -31,8 +31,7 @@ use cbor::cbor_array_vec;
 use core::cmp;
 use core::convert::TryInto;
 use crypto::rng256::Rng256;
-use persistent_store::fragment::{read_range, write};
-use persistent_store::StoreUpdate;
+use persistent_store::{fragment, StoreUpdate};
 
 // Those constants may be modified before compilation to tune the behavior of the key.
 //
@@ -485,14 +484,14 @@ impl PersistentStore {
         byte_count: usize,
     ) -> Result<Vec<u8>, Ctap2StatusCode> {
         let byte_range = offset..offset + byte_count;
-        let output = read_range(&self.store, &key::LARGE_BLOB_SHARDS, byte_range)?;
+        let output = fragment::read_range(&self.store, &key::LARGE_BLOB_SHARDS, byte_range)?;
         Ok(output.unwrap_or_else(|| {
-            let empty_large_blob = vec![
+            const EMPTY_LARGE_BLOB: [u8; 17] = [
                 0x80, 0x76, 0xBE, 0x8B, 0x52, 0x8D, 0x00, 0x75, 0xF7, 0xAA, 0xE9, 0x8D, 0x6F, 0xA5,
                 0x7A, 0x6D, 0x3C,
             ];
-            let last_index = cmp::min(empty_large_blob.len(), offset + byte_count);
-            empty_large_blob
+            let last_index = cmp::min(EMPTY_LARGE_BLOB.len(), offset + byte_count);
+            EMPTY_LARGE_BLOB
                 .get(offset..last_index)
                 .unwrap_or_default()
                 .to_vec()
@@ -508,7 +507,7 @@ impl PersistentStore {
         if large_blob_array.len() > MAX_LARGE_BLOB_ARRAY_SIZE {
             return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
         }
-        Ok(write(
+        Ok(fragment::write(
             &mut self.store,
             &key::LARGE_BLOB_SHARDS,
             large_blob_array,