diff --git a/lib/sproxyd.js b/lib/sproxyd.js
index 62ff1bd..5d6e112 100644
--- a/lib/sproxyd.js
+++ b/lib/sproxyd.js
@@ -237,7 +237,7 @@ class SproxydClient {
         // when current endpoint matches the endpoint of the failed request
         const currentBootstrap = this.getCurrentBootstrap();
 
-        this._handleRequest(method, stream, size, key, log, (err, ret) => {
+        this._handleRequest(method, stream, size, key, log, (err, ...rest) => {
             if (err && !err.isExpected) {
                 if (receivedResponse === true) {
                     log.fatal('multiple responses from sproxyd, trying to '
@@ -273,7 +273,7 @@ class SproxydClient {
             }
             receivedResponse = true;
             log.end().debug('request received response');
-            return callback(err, ret);
+            return callback(err, ...rest);
         }, args, payload);
     }
 
@@ -315,11 +315,10 @@ class SproxydClient {
                     }
                     return callback(errorProcessed);
                 }
-                // We return the key
                 log.debug('stored to sproxyd', {
                     statusCode: response.statusCode,
                 });
-                return callback(null, newKey);
+                return callback(null, newKey, response);
             });
 
             const startPayloadStreaming = () => {
@@ -420,11 +419,13 @@ class SproxydClient {
      */
     put(stream, size, params, reqUids, callback, keyScheme) {
         const log = this.createLogger(reqUids);
-        this._failover('PUT', stream, size, keyScheme, 0, log, (err, key) => {
+        this._failover('PUT', stream, size, keyScheme, 0, log, (err, key, response) => {
             if (err) {
                 return callback(err);
             }
-            return callback(null, key);
+            const version = response && response.headers
+                ? response.headers['x-scal-version'] : undefined;
+            return callback(null, key, version);
         }, params);
     }
 
@@ -455,6 +456,24 @@ class SproxydClient {
         }, reqParams);
     }
 
+    /**
+     * Update the user metadata of an existing object without replacing its content.
+     * Sends a zero-byte PUT with x-scal-cmd: update-usermd.
+     * @param {string} keyScheme - sproxyd key
+     * @param {string} metadata - metadata to set in x-scal-usermd header
+     * @param {string} reqUids - The serialized request id
+     * @param {SproxydClient~putCallback} callback - callback
+     * @returns {undefined}
+     */
+    putUserMetadata(keyScheme, metadata, params, reqUids, callback) {
+        const reqParams = Object.assign({}, params, {
+            headers: Object.assign({}, params && params.headers, {
+                'x-scal-cmd': 'update-usermd',
+            }),
+        });
+        this.putEmptyObject(keyScheme, metadata, reqParams, reqUids, callback);
+    }
+
     /**
      * This sends a GET request to sproxyd.
      * @param {String} key - The key associated to the value
diff --git a/package.json b/package.json
index ed738cf..a5c3f18 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
   "engines": {
     "node": ">=20"
   },
-  "version": "9.0.0",
+  "version": "9.1.0",
   "description": "sproxyd client",
   "main": "index.js",
   "scripts": {
diff --git a/tests/unit/sproxyd.js b/tests/unit/sproxyd.js
index 068ee24..35750fe 100644
--- a/tests/unit/sproxyd.js
+++ b/tests/unit/sproxyd.js
@@ -131,16 +131,25 @@ function handler(req, res) {
                 return;
             }
         }
-        server[key] = Buffer.alloc(0);
-        if (req.headers['x-scal-usermd']) {
-            md[key] = req.headers['x-scal-usermd'];
-        }
-        versions[key] = (versions[key] || 0) + 64;
-        req.on('data', data => {
-            server[key] = Buffer.concat([server[key], data]);
-        })
-            .on('end', () => makeResponse(res, 200, 'OK', null, null,
+        if (req.headers['x-scal-cmd'] === 'update-usermd') {
+            if (req.headers['x-scal-usermd']) {
+                md[key] = req.headers['x-scal-usermd'];
+            }
+            versions[key] = (versions[key] || 0) + 64;
+            req.resume().on('end', () => makeResponse(res, 200, 'OK', null, null,
                 versions[key]));
+        } else {
+            server[key] = Buffer.alloc(0);
+            if (req.headers['x-scal-usermd']) {
+                md[key] = req.headers['x-scal-usermd'];
+            }
+            versions[key] = (versions[key] || 0) + 64;
+            req.on('data', data => {
+                server[key] = Buffer.concat([server[key], data]);
+            })
+                .on('end', () => makeResponse(res, 200, 'OK', null, null,
+                    versions[key]));
+        }
     } else if (req.method === 'GET') {
         if (!server[key]) {
             consumeAndMakeResponse(req, res, 404, 'NoSuchPath');
@@ -323,6 +332,45 @@ const clientImmutableWithFailover = new Sproxy({
             });
         });
 
+        it('should update user metadata via putUserMetadata without altering content', done => {
+            const newMd = generateMD();
+            let testKey;
+            let initialVersion;
+            const upStream = new stream.PassThrough();
+            upStream.write(upload);
+            upStream.end();
+            async.series([
+                next => client.put(upStream, upload.length, parameters, reqUid,
+                    (err, key, version) => {
+                        testKey = key;
+                        initialVersion = version;
+                        next(err);
+                    }),
+                next => client.putUserMetadata(testKey, newMd,
+                    { query: { version: initialVersion } }, reqUid, next),
+                next => client.getUserMetadata(testKey, reqUid, (err, data) => {
+                    assert.strictEqual(data, newMd);
+                    next(err);
+                }),
+                next => checkKeyContent(client, testKey, upload, reqUid, next),
+            ], done);
+        });
+
+        it('should fail putUserMetadata with wrong version', done => {
+            const upStream = new stream.PassThrough();
+            upStream.write(upload);
+            upStream.end();
+            async.waterfall([
+                next => client.put(upStream, upload.length, parameters, reqUid, next),
+                (key, version, next) => client.putUserMetadata(key, generateMD(),
+                    { query: { version: 0 } }, reqUid, err => {
+                        assert(err, 'expected error for wrong version');
+                        assert.strictEqual(err.code, 412);
+                        next();
+                    }),
+            ], done);
+        });
+
         it('Get HEAD should return an error', done => {
             client.getUserMetadata(generateKey(), reqUid, err => {
                 assert.notStrictEqual(err, null);