diff --git a/lib/extend.js b/lib/extend.js
index a5498717f..4bb489ed9 100755
--- a/lib/extend.js
+++ b/lib/extend.js
@@ -34,27 +34,28 @@ exports.root = function (root, extensions) {
 
         root.assert(extension, Schemas.extension);
 
-        const base = (extension.base || root.any()).clone(); // Cloning because we're going to override messages afterwards
+        const base = extension.base || root.any();
         const ctor = base.constructor;
-        const type = class extends ctor { // eslint-disable-line no-loop-func
+        const type = class extends ctor {                       // eslint-disable-line no-loop-func
 
             constructor() {
 
                 super();
 
                 if (extension.base) {
-                    Object.assign(this, base);
+                    Object.assign(this, extension.base);
                 }
 
                 this._type = extension.name;
+
+                if (extension.messages) {
+                    const existing = base._preferences && Hoek.clone(base._preferences.messages);
+                    this._preferences = Object.assign({}, this._preferences);
+                    this._preferences.messages = Messages.compile(extension.messages, existing);
+                }
             }
         };
 
-        if (extension.messages) {
-            const existing = type.prototype._messages || base._preferences && base._preferences.messages;
-            type.prototype._messages = Messages.compile(extension.messages, existing);
-        }
-
         if (extension.coerce) {
             type.prototype._coerce = function (value, state, prefs) {
 
diff --git a/lib/validator.js b/lib/validator.js
index cbfb1bb93..2c52b67c1 100755
--- a/lib/validator.js
+++ b/lib/validator.js
@@ -358,7 +358,7 @@ internals.prefs = function (schema, prefs) {
             return schema._preferences[Common.symbols.prefs];
         }
 
-        prefs = Common.preferences(schema._messages ? Common.preferences({ messages: schema._messages }, prefs) : prefs, schema._preferences);
+        prefs = Common.preferences(prefs, schema._preferences);
         if (isDefaultOptions) {
             schema._preferences[Common.symbols.prefs] = prefs;
         }
@@ -366,10 +366,6 @@ internals.prefs = function (schema, prefs) {
         return prefs;
     }
 
-    if (schema._messages) {
-        return Common.preferences({ messages: schema._messages }, prefs);
-    }
-
     return prefs;
 };
 
diff --git a/test/extend.js b/test/extend.js
index 4c182e8f1..dff3a5d96 100755
--- a/test/extend.js
+++ b/test/extend.js
@@ -534,7 +534,7 @@ describe('extension', () => {
         expect(schema.validate(3)).to.contain({ error: null, value: 6 });
     });
 
-    it('does not override a predefined messages', () => {
+    it('overrides base messages', () => {
 
         const base = Joi.any().prefs({
             messages: {
@@ -566,7 +566,7 @@ describe('extension', () => {
         const schema = customJoi.myType().foo();
         const result = schema.validate({});
         expect(result.error).to.be.an.instanceof(Error);
-        expect(result.error.toString()).to.equal('ValidationError: "value" original');
+        expect(result.error.toString()).to.equal('ValidationError: "value" modified');
     });
 
     it('does not change predefined options', () => {