diff --git a/lib/relation-definition.js b/lib/relation-definition.js
index cbb87653..0651ef8b 100644
--- a/lib/relation-definition.js
+++ b/lib/relation-definition.js
@@ -1417,7 +1417,7 @@ RelationDefinition.hasOne = function (modelFrom, modelTo, params) {
   params = params || {};
   modelTo = lookupModelTo(modelFrom, modelTo, params);
 
-  var pk = modelTo.dataSource.idName(modelTo.modelName) || 'id';
+  var pk = modelFrom.dataSource.idName(modelFrom.modelName) || 'id';
   var relationName = params.as || i8n.camelize(modelTo.modelName, true);
 
   var fk = params.foreignKey || i8n.camelize(modelFrom.modelName + '_id', true);
@@ -2748,4 +2748,4 @@ ReferencesMany.prototype.remove = function (acInst, cb) {
   } else {
     process.nextTick(function() { cb(null, ids); });
   }
-};
\ No newline at end of file
+};