diff --git a/src/api/common/signature/checksum.rs b/src/api/common/signature/checksum.rs
index 464fdc75..d223175f 100644
--- a/src/api/common/signature/checksum.rs
+++ b/src/api/common/signature/checksum.rs
@@ -28,8 +28,8 @@ pub const X_AMZ_CHECKSUM_SHA1: HeaderName = HeaderName::from_static("x-amz-check
 pub const X_AMZ_CHECKSUM_SHA256: HeaderName = HeaderName::from_static("x-amz-checksum-sha256");
 
 // Values for x-amz-checksum-type
-pub const COMPOSITE: &[u8] = b"COMPOSITE";
-pub const FULL_OBJECT: &[u8] = b"FULL_OBJECT";
+pub const COMPOSITE: &str = "COMPOSITE";
+pub const FULL_OBJECT: &str = "FULL_OBJECT";
 
 pub type Crc32Checksum = [u8; 4];
 pub type Crc32cChecksum = [u8; 4];
diff --git a/src/api/s3/multipart.rs b/src/api/s3/multipart.rs
index 4fea1c44..bb00f066 100644
--- a/src/api/s3/multipart.rs
+++ b/src/api/s3/multipart.rs
@@ -518,6 +518,11 @@ pub async fn handle_complete_multipart_upload(
 			Some(ChecksumValue::Sha256(x)) => Some(s3_xml::Value(BASE64_STANDARD.encode(&x))),
 			_ => None,
 		},
+		checksum_type: match checksum_algorithm {
+			Some((_, ChecksumType::Composite)) => Some(s3_xml::Value(COMPOSITE.into())),
+			Some((_, ChecksumType::FullObject)) => Some(s3_xml::Value(FULL_OBJECT.into())),
+			None => None,
+		},
 	};
 	let xml = s3_xml::to_xml_with_header(&result)?;
 
@@ -691,8 +696,8 @@ pub fn request_checksum_algorithm_and_type(
 		)),
 		(Some(x), Some(algo)) => {
 			let checksum_type = match x.as_bytes() {
-				COMPOSITE => ChecksumType::Composite,
-				FULL_OBJECT => ChecksumType::FullObject,
+				x if x == COMPOSITE.as_bytes() => ChecksumType::Composite,
+				x if x == FULL_OBJECT.as_bytes() => ChecksumType::FullObject,
 				_ => return Err(Error::bad_request("Invalid x-amz-checksum-type value")),
 			};
 			match (checksum_type, algo) {
diff --git a/src/api/s3/xml.rs b/src/api/s3/xml.rs
index 7dea3d1c..6c1d8f88 100644
--- a/src/api/s3/xml.rs
+++ b/src/api/s3/xml.rs
@@ -141,6 +141,8 @@ pub struct CompleteMultipartUploadResult {
 	pub checksum_sha1: Option<Value>,
 	#[serde(rename = "ChecksumSHA256")]
 	pub checksum_sha256: Option<Value>,
+	#[serde(rename = "ChecksumType")]
+	pub checksum_type: Option<Value>,
 }
 
 #[derive(Debug, Serialize, PartialEq, Eq)]
@@ -514,6 +516,7 @@ mod tests {
 
 	#[test]
 	fn complete_multipart_upload_result() -> Result<(), ApiError> {
+		use garage_api_common::signature::checksum::COMPOSITE;
 		let result = CompleteMultipartUploadResult {
 			xmlns: (),
 			location: Some(Value("https://garage.tld/mybucket/a/plop".to_string())),
@@ -525,6 +528,7 @@ mod tests {
 			checksum_crc64nvme: None,
 			checksum_sha1: Some(Value("ZJAnHyG8PeKz9tI8UTcHrJos39A=".into())),
 			checksum_sha256: None,
+			checksum_type: Some(Value(COMPOSITE.into())),
 		};
 		assert_eq!(
 			to_xml_with_header(&result)?,
@@ -535,6 +539,7 @@ mod tests {
 	<Key>a/plop</Key>\
 	<ETag>&quot;3858f62230ac3c915f300c664312c11f-9&quot;</ETag>\
     <ChecksumSHA1>ZJAnHyG8PeKz9tI8UTcHrJos39A=</ChecksumSHA1>\
+    <ChecksumType>COMPOSITE</ChecksumType>\
 </CompleteMultipartUploadResult>"
 		);
 		Ok(())