diff --git a/packages/backend/native/src/runtime/storage_runtime/mod.rs b/packages/backend/native/src/runtime/storage_runtime/mod.rs
index 3dda90f844..83e351ed4d 100644
--- a/packages/backend/native/src/runtime/storage_runtime/mod.rs
+++ b/packages/backend/native/src/runtime/storage_runtime/mod.rs
@@ -23,7 +23,7 @@ pub(crate) mod object_storage;
 
 use self::object_storage::{
   ObjectStorageConfig, StorageProviderConfig,
-  types::{ObjectGetResult, ObjectListEntry, ObjectMetadata, ObjectPutMetadata},
+  types::{ObjectGetResult, ObjectListEntry, ObjectMetadata, ObjectPutMetadata, checksum_crc32_base64},
 };
 pub(super) use super::{
   RuntimeError, RuntimeResult,
@@ -1081,7 +1081,7 @@ fn fs_put(config: &FsStorageConfig, key: &str, body: Vec<u8>, metadata: ObjectPu
     return Err(RuntimeError::invalid_input("StorageRuntime fs content length mismatch"));
   }
   if let Some(checksum) = metadata.checksum_crc32.as_deref() {
-    let actual = format!("{:x}", crc32fast::hash(&body));
+    let actual = checksum_crc32_base64(&body);
     if actual != checksum {
       return Err(RuntimeError::invalid_input("StorageRuntime fs checksum mismatch"));
     }
@@ -1439,7 +1439,7 @@ mod tests {
       bucket: "bucket".to_string(),
     };
     let body = b"hello".to_vec();
-    let checksum = format!("{:x}", crc32fast::hash(&body));
+    let checksum = checksum_crc32_base64(&body);
 
     fs_put(
       &config,
@@ -1741,7 +1741,7 @@ mod tests {
       ObjectPutMetadata {
         content_type: Some("text/plain".to_string()),
         content_length: Some(body.len() as i64),
-        checksum_crc32: Some(format!("{:x}", crc32fast::hash(&body))),
+        checksum_crc32: Some(checksum_crc32_base64(&body)),
       },
     )
     .await?;
diff --git a/packages/backend/native/src/runtime/storage_runtime/object_storage/tests.rs b/packages/backend/native/src/runtime/storage_runtime/object_storage/tests.rs
index dea7f55972..f1d1f7f0c7 100644
--- a/packages/backend/native/src/runtime/storage_runtime/object_storage/tests.rs
+++ b/packages/backend/native/src/runtime/storage_runtime/object_storage/tests.rs
@@ -3,7 +3,10 @@ use reqwest::StatusCode;
 use super::{
   config::ObjectStorageConfig,
   error::ObjectStorageError,
-  types::{MultipartUploadPart, ObjectPutMetadata, StorageProviderConfig, completed_multipart_parts, trim_etag},
+  types::{
+    MultipartUploadPart, ObjectPutMetadata, StorageProviderConfig, checksum_crc32_base64, completed_multipart_parts,
+    trim_etag,
+  },
 };
 
 fn storage_config(provider: &str, config: serde_json::Value) -> StorageProviderConfig {
@@ -365,3 +368,9 @@ fn object_storage_orders_completed_multipart_parts_and_trims_etags() {
   assert_eq!(parts[1].part_number, 2);
   assert_eq!(parts[1].etag, "b");
 }
+
+#[test]
+fn object_storage_crc32_checksum_uses_s3_base64_format() {
+  assert_eq!(checksum_crc32_base64(b"hello"), "NhCmhg==");
+  assert_ne!(checksum_crc32_base64(b"hello"), "3610a686");
+}
diff --git a/packages/backend/native/src/runtime/storage_runtime/object_storage/types.rs b/packages/backend/native/src/runtime/storage_runtime/object_storage/types.rs
index b71b1575a4..a6775a4f78 100644
--- a/packages/backend/native/src/runtime/storage_runtime/object_storage/types.rs
+++ b/packages/backend/native/src/runtime/storage_runtime/object_storage/types.rs
@@ -1,5 +1,6 @@
 use std::collections::HashMap;
 
+use base64::{Engine as _, engine::general_purpose::STANDARD};
 use serde::Deserialize;
 
 use super::super::{
@@ -90,9 +91,7 @@ impl From<RuntimeObjectStoragePutOptions> for ObjectPutMetadata {
 impl ObjectPutMetadata {
   pub(crate) fn complete_for_body(mut self, body: &[u8]) -> Self {
     self.content_length.get_or_insert(body.len() as i64);
-    self
-      .checksum_crc32
-      .get_or_insert_with(|| format!("{:x}", crc32fast::hash(body)));
+    self.checksum_crc32.get_or_insert_with(|| checksum_crc32_base64(body));
     self
       .content_type
       .get_or_insert_with(|| crate::file_type::get_mime(body));
@@ -111,6 +110,10 @@ impl ObjectPutMetadata {
   }
 }
 
+pub(crate) fn checksum_crc32_base64(body: &[u8]) -> String {
+  STANDARD.encode(crc32fast::hash(body).to_be_bytes())
+}
+
 impl From<ObjectMetadata> for RuntimeObjectMetadata {
   fn from(metadata: ObjectMetadata) -> Self {
     Self {