diff --git a/lib/adapters/postgres.js b/lib/adapters/postgres.js
index 8bbb8d54..52701e04 100644
--- a/lib/adapters/postgres.js
+++ b/lib/adapters/postgres.js
@@ -164,7 +164,18 @@ PG.prototype.toDatabase = function (prop, val) {
             return this.toDatabase(prop, val[0]) + ' AND ' + this.toDatabase(prop, val[1]);
         }
     }
-    if (prop.type.name === 'Number') return val;
+    if (prop.type.name === 'Number') {
+      if (!val) {
+          if( prop.autoIncrement ) {
+              return 'DEFAULT';
+          }
+          else {
+              return 'NULL';
+          }
+      }
+      return val
+    };
+
     if (prop.type.name === 'Date') {
         if (!val) {
             if( prop.autoIncrement ) {