diff --git a/js/model.js b/js/model.js
index a74db7158f..be33b54f4a 100644
--- a/js/model.js
+++ b/js/model.js
@@ -486,7 +486,7 @@
     Sao.field.Float = Sao.class_(Sao.field.Number, {
         set_client: function(record, value) {
             if (typeof value == 'string') {
-                value = Number(value); // without new for type conversion
+                value = Number(value);
                 if (isNaN(value)) {
                     value = this._default;
                 }
@@ -507,7 +507,7 @@
     Sao.field.Numeric = Sao.class_(Sao.field.Number, {
         set_client: function(record, value) {
             if (typeof value == 'string') {
-                value = new Number(value); // with new to get an instance
+                value = new Sao.Decimal(value);
                 if (isNaN(value.valueOf())) {
                     value = this._default;
                 }
diff --git a/js/rpc.js b/js/rpc.js
index 51117102dd..04ca7dad2c 100644
--- a/js/rpc.js
+++ b/js/rpc.js
@@ -81,7 +81,7 @@
                    case 'buffer':
                        throw new Error('Buffer support not implemented');
                    case 'Decimal':
-                       value = new Number(value.decimal);
+                       value = new Sao.Decimal(value.decimal);
                        break;
                }
                if (parent) {
@@ -125,7 +125,7 @@
                 if (parent) {
                     parent[index] = value;
                 }
-            } else if (value instanceof Number) {
+            } else if (value instanceof Sao.Decimal) {
                 value = {
                     '__class__': 'Decimal',
                     'decimal': value.valueOf()
diff --git a/js/sao.js b/js/sao.js
index ca50c919ff..354fb934fb 100644
--- a/js/sao.js
+++ b/js/sao.js
@@ -32,4 +32,6 @@ var Sao = {};
         }
         return ClassConstructor;
     };
+
+    Sao.Decimal = Number;
 }());
diff --git a/tests/sao.js b/tests/sao.js
index 56f0c24b1a..6ee6c14118 100644
--- a/tests/sao.js
+++ b/tests/sao.js
@@ -25,7 +25,7 @@
             },
             'datetime': new Date(2012, 11, 29, 19, 59, 10),
             'date': new Date(2012, 11, 29),
-            'decimal': new Number(1.1)
+            'decimal': new Sao.Decimal(1.1)
         };
         for (var name in tests) {
             var test = tests[name];