diff --git a/packages/storage/__tests__/AwsClients/S3/cases/listParts.ts b/packages/storage/__tests__/AwsClients/S3/cases/listParts.ts
index 0ff6327a329..e27b11e7ada 100644
--- a/packages/storage/__tests__/AwsClients/S3/cases/listParts.ts
+++ b/packages/storage/__tests__/AwsClients/S3/cases/listParts.ts
@@ -36,10 +36,12 @@ const listPartsHappyCase: ApiFunctionalTestCase<typeof listParts> = [
 			'<Part>' +
 			'<PartNumber>1</PartNumber>' +
 			'<ETag>etag1</ETag>' +
+			'<Size>5242880</Size>' +
 			'</Part>' +
 			'<Part>' +
 			'<PartNumber>2</PartNumber>' +
 			'<ETag>etag2</ETag>' +
+			'<Size>1024</Size>' +
 			'</Part>' +
 			'</ListPartsResult>',
 	},
@@ -50,10 +52,12 @@ const listPartsHappyCase: ApiFunctionalTestCase<typeof listParts> = [
 			{
 				PartNumber: 1,
 				ETag: 'etag1',
+				Size: 5242880,
 			},
 			{
 				PartNumber: 2,
 				ETag: 'etag2',
+				Size: 1024,
 			},
 		],
 	},
diff --git a/packages/storage/src/AwsClients/S3/listParts.ts b/packages/storage/src/AwsClients/S3/listParts.ts
index 0493fcae59c..3cb5a718352 100644
--- a/packages/storage/src/AwsClients/S3/listParts.ts
+++ b/packages/storage/src/AwsClients/S3/listParts.ts
@@ -84,6 +84,7 @@ const deserializeCompletedPartList = (input: any[]): CompletedPart[] =>
 		map(item, {
 			PartNumber: ['PartNumber', deserializeNumber],
 			ETag: 'ETag',
+			Size: ['Size', deserializeNumber],
 		})
 	);