diff --git a/core/src/main/java/com/backblaze/b2/client/B2StorageClientWebifierImpl.java b/core/src/main/java/com/backblaze/b2/client/B2StorageClientWebifierImpl.java
index 7edfab034..bd3b78697 100644
--- a/core/src/main/java/com/backblaze/b2/client/B2StorageClientWebifierImpl.java
+++ b/core/src/main/java/com/backblaze/b2/client/B2StorageClientWebifierImpl.java
@@ -280,6 +280,9 @@ public B2FileVersion uploadFile(B2UploadUrlResponse uploadUrlResponse,
             if (request.getLegalHold() != null) {
                 headersBuilder.set(B2Headers.FILE_LEGAL_HOLD,
                         request.getLegalHold());
+                // TODO: remove after production has transitioned fully to use newer header
+                headersBuilder.set("X-Bz-File-Lock-Legal-Hold-Status",
+                        request.getLegalHold());
             }
 
             if (request.getFileRetention() != null) {
@@ -289,6 +292,11 @@ public B2FileVersion uploadFile(B2UploadUrlResponse uploadUrlResponse,
                         request.getFileRetention().getMode());
                 headersBuilder.set(B2Headers.FILE_RETENTION_RETAIN_UNTIL_TIMESTAMP,
                         request.getFileRetention().getRetainUntilTimestamp().toString());
+                // TODO: remove after production has transitioned fully to use newer headers
+                headersBuilder.set("X-Bz-File-Lock-Retention-Mode",
+                        request.getFileRetention().getMode());
+                headersBuilder.set("X-Bz-File-Lock-Retention-Retain-Until-Timestamp",
+                        request.getFileRetention().getRetainUntilTimestamp().toString());
             }
 
             // if the source provides a last-modified time, add it.
diff --git a/core/src/test/java/com/backblaze/b2/client/B2StorageClientWebifierImplTest.java b/core/src/test/java/com/backblaze/b2/client/B2StorageClientWebifierImplTest.java
index fac30a638..5848eb7fa 100644
--- a/core/src/test/java/com/backblaze/b2/client/B2StorageClientWebifierImplTest.java
+++ b/core/src/test/java/com/backblaze/b2/client/B2StorageClientWebifierImplTest.java
@@ -1681,6 +1681,9 @@ public void testUploadFileWithFileLockInfo() throws B2Exception {
                 "    User-Agent: SecretAgentMan/3.19.28\n" +
                 "    X-Bz-Content-Sha1: 0a0a9f2a6772942557ab5355d76af442f8f65e01\n" +
                 "    X-Bz-File-Legal-Hold: on\n" +
+                "    X-Bz-File-Lock-Legal-Hold-Status: on\n" +
+                "    X-Bz-File-Lock-Retention-Mode: governance\n" +
+                "    X-Bz-File-Lock-Retention-Retain-Until-Timestamp: 9876543210\n" +
                 "    X-Bz-File-Name: files/%E8%87%AA%E7%94%B1/0001\n" +
                 "    X-Bz-File-Retention-Mode: governance\n" +
                 "    X-Bz-File-Retention-Retain-Until-Timestamp: 9876543210\n" +