diff --git a/lib/relation-definition.js b/lib/relation-definition.js
index b022072a..719bf637 100644
--- a/lib/relation-definition.js
+++ b/lib/relation-definition.js
@@ -1406,21 +1406,19 @@ RelationDefinition.embedsMany = function hasMany(modelFrom, modelTo, params) {
     type: [modelTo], default: function() { return []; } 
   });
   
-  // require explicit/unique ids unless autoId === true
-  if (definition.options.autoId === false) {
-    modelTo.validatesPresenceOf(idName);
-    modelFrom.validate(relationName, function(err) {
-      var embeddedList = this[relationName] || [];
-      var ids = embeddedList.map(function(m) { return m[idName]; });
-      var uniqueIds = ids.filter(function(id, pos) {
-          return ids.indexOf(id) === pos;
-      });
-      if (ids.length !== uniqueIds.length) {
-        this.errors.add(relationName, 'Contains duplicate `' + idName + '`', 'uniqueness');
-        err(false);
-      }
-    }, { code: 'uniqueness' })
-  }
+  // unique id is required
+  modelTo.validatesPresenceOf(idName);
+  modelFrom.validate(relationName, function(err) {
+    var embeddedList = this[relationName] || [];
+    var ids = embeddedList.map(function(m) { return m[idName]; });
+    var uniqueIds = ids.filter(function(id, pos) {
+        return ids.indexOf(id) === pos;
+    });
+    if (ids.length !== uniqueIds.length) {
+      this.errors.add(relationName, 'Contains duplicate `' + idName + '`', 'uniqueness');
+      err(false);
+    }
+  }, { code: 'uniqueness' })
   
   // validate all embedded items
   if (definition.options.validate) {