diff --git a/lib/delta-with-metadata.js b/lib/delta-with-metadata.js
index 99aaabb..a89b2be 100644
--- a/lib/delta-with-metadata.js
+++ b/lib/delta-with-metadata.js
@@ -14,7 +14,7 @@ var DeltaWithMetadata = function (obj) {
   if (!obj) return;
 
   for (var key in config.serializedProperties) {
-    if (config.serializedProperties[key]) this[key] = obj[key];
+    if (config.serializedProperties[key] && obj[key] !== undefined) this[key] = obj[key];
   }
 };
 
diff --git a/lib/type.js b/lib/type.js
index 9933a39..65589aa 100644
--- a/lib/type.js
+++ b/lib/type.js
@@ -14,17 +14,14 @@ module.exports = {
     },
 
     apply: function (snapshot, delta) {
-      const metadata = snapshot && snapshot.metadata;
-
-      snapshot = new Delta(snapshot);
       delta = new Delta(delta);
-      snapshot = snapshot.compose(delta);
+      var composed = new Delta(snapshot).compose(delta);
 
-      if (metadata) {
-        snapshot.metadata = metadata;
+      for (var key in config.serializedProperties) {
+        if (config.serializedProperties[key] && snapshot[key] !== undefined) composed[key] = snapshot[key];
       }
 
-      return snapshot;
+      return composed;
     },
 
     compose: function (delta1, delta2) {
@@ -58,7 +55,7 @@ module.exports = {
       var serialized = {ops: delta.ops};
 
       for (var key in config.serializedProperties) {
-        if (config.serializedProperties[key]) serialized[key] = delta[key];
+        if (config.serializedProperties[key] && delta[key] !== undefined) serialized[key] = delta[key];
       }
 
       return serialized;
diff --git a/package.json b/package.json
index fb484e2..270fa0e 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@reedsy/rich-text",
-  "version": "4.1.0-reedsy.3.1.0",
+  "version": "4.1.0-reedsy.4.0.0",
   "description": "OT type for rich text",
   "author": "Jason Chen <jhchen7@gmail.com>",
   "homepage": "https://github.com/ottypes/rich-text",
diff --git a/test/config.js b/test/config.js
index b2fc1f3..d49699f 100644
--- a/test/config.js
+++ b/test/config.js
@@ -4,6 +4,10 @@ var sinon = require('sinon');
 const config = require('../lib/config');
 
 describe('config', function() {
+  afterEach(function() {
+    sinon.restore();
+  });
+
   describe('serialization', function() {
     it('serializes metadata by default', function() {
       var delta = richText.create();
@@ -28,7 +32,6 @@ describe('config', function() {
       delta.$doNotSerialize = {foo: '123'};
       expect(richText.serialize(delta)).to.eql({
         ops: [],
-        metadata: undefined,
       });
     });
 
@@ -63,4 +66,46 @@ describe('config', function() {
       expect(delta.extra).to.eql({lorem: 'ipsum'});
     });
   });
+
+  describe('apply', () => {
+    it('keeps metadata when applying a delta to a snapshot', function() {
+      var snapshot = {
+        ops: [{insert: '\n'}],
+        metadata: {abc: 123},
+      };
+      var delta = {ops: [{insert: 'foo'}]};
+      var applied = richText.apply(snapshot, delta);
+      expect(applied).to.eql({
+        ops: [{insert: 'foo\n'}],
+        metadata: {abc: 123},
+      });
+    });
+
+    it('drops unspecified props when applying a delta to a snapshot', function () {
+      var snapshot = {
+        ops: [{insert: '\n'}],
+        extra: {abc: 123},
+      };
+      var delta = {ops: [{insert: 'foo'}]};
+      var applied = richText.apply(snapshot, delta);
+      expect(applied).to.eql({
+        ops: [{insert: 'foo\n'}],
+      });
+    });
+
+    it('can specify extra props to keep when applying a delta to a snapshot', function () {
+      sinon.stub(config, 'serializedProperties').get(() => ({extra: true}));
+
+      var snapshot = {
+        ops: [{insert: '\n'}],
+        extra: {abc: 123},
+      };
+      var delta = {ops: [{insert: 'foo'}]};
+      var applied = richText.apply(snapshot, delta);
+      expect(applied).to.eql({
+        ops: [{insert: 'foo\n'}],
+        extra: {abc: 123},
+      });
+    });
+  });
 });