diff --git a/lib/server.js b/lib/server.js
index 8aaf92e..c956306 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -480,6 +480,7 @@ WalletService.prototype.savePreferences = function(opts, cb) {
     },
   }];
 
+  opts = _.pick(opts, _.pluck(preferences, 'name'));
   try {
     _.each(preferences, function(preference) {
       var value = opts[preference.name];
@@ -494,15 +495,17 @@ WalletService.prototype.savePreferences = function(opts, cb) {
   }
 
   self._runLocked(cb, function(cb) {
-    var preferences = Model.Preferences.create({
-      walletId: self.walletId,
-      copayerId: self.copayerId,
-      email: opts.email,
-      language: opts.language,
-      unit: opts.unit,
-    });
-    self.storage.storePreferences(preferences, function(err) {
-      return cb(err);
+    self.storage.fetchPreferences(self.walletId, self.copayerId, function(err, oldPref) {
+      if (err) return cb(err);
+
+      var newPref = Model.Preferences.create({
+        walletId: self.walletId,
+        copayerId: self.copayerId,
+      });
+      var preferences = Model.Preferences.fromObj(_.defaults(newPref, opts, oldPref));
+      self.storage.storePreferences(preferences, function(err) {
+        return cb(err);
+      });
     });
   });
 };
diff --git a/test/integration/server.js b/test/integration/server.js
index 1654708..aa6d56e 100644
--- a/test/integration/server.js
+++ b/test/integration/server.js
@@ -1160,6 +1160,7 @@ describe('Wallet service', function() {
         email: 'dummy@dummy.com',
         language: 'es',
         unit: 'bit',
+        dummy: 'ignored',
       }, function(err) {
         should.not.exist(err);
         server.getPreferences({}, function(err, preferences) {
@@ -1168,6 +1169,7 @@ describe('Wallet service', function() {
           preferences.email.should.equal('dummy@dummy.com');
           preferences.language.should.equal('es');
           preferences.unit.should.equal('bit');
+          should.not.exist(preferences.dummy);
           done();
         });
       });
@@ -1186,6 +1188,58 @@ describe('Wallet service', function() {
         });
       });
     });
+    it('should save preferences incrementally', function(done) {
+      async.series([
+
+        function(next) {
+          server.savePreferences({
+            email: 'dummy@dummy.com',
+          }, next);
+        },
+        function(next) {
+          server.getPreferences({}, function(err, preferences) {
+            should.not.exist(err);
+            should.exist(preferences);
+            preferences.email.should.equal('dummy@dummy.com');
+            should.not.exist(preferences.language);
+            next();
+          });
+        },
+        function(next) {
+          server.savePreferences({
+            language: 'es',
+          }, next);
+        },
+        function(next) {
+          server.getPreferences({}, function(err, preferences) {
+            should.not.exist(err);
+            should.exist(preferences);
+            preferences.language.should.equal('es');
+            preferences.email.should.equal('dummy@dummy.com');
+            next();
+          });
+        },
+        function(next) {
+          server.savePreferences({
+            language: null,
+            unit: 'bit',
+          }, next);
+        },
+        function(next) {
+          server.getPreferences({}, function(err, preferences) {
+            should.not.exist(err);
+            should.exist(preferences);
+            preferences.unit.should.equal('bit');
+            should.not.exist(preferences.language);
+            preferences.email.should.equal('dummy@dummy.com');
+            next();
+          });
+        },
+      ], function(err) {
+        should.not.exist(err);
+        done();
+      });
+    });
     it.skip('should save preferences only for requesting wallet', function(done) {});
     it('should validate entries', function(done) {
       var invalid = [{