diff --git a/lib/relation-definition.js b/lib/relation-definition.js
index bace4705..aa42e086 100644
--- a/lib/relation-definition.js
+++ b/lib/relation-definition.js
@@ -398,6 +398,25 @@ function lookupModel(models, modelName) {
   }
 }
 
+function lookupModelTo(modelFrom, modelTo, params, singularize) {
+  if ('string' === typeof modelTo) {
+    params.as = params.as || modelTo;
+    if (typeof params.model === 'function') {
+      modelTo = params.model;
+    } else if (typeof params.model === 'string') {
+      modelTo = params.model;
+    }
+    if (typeof modelTo === 'string') {
+      var modelToName = (singularize ? i8n.singularize(modelTo) : modelTo).toLowerCase();
+      modelTo = lookupModel(modelFrom.dataSource.modelBuilder.models, modelToName) || modelTo;
+    }
+    if (typeof modelTo === 'string') {
+      throw new Error('Could not find "' + modelTo + '" relation for ' + modelFrom.modelName);
+    }
+  }
+  return modelTo;
+}
+
 /*!
  * Normalize polymorphic parameters
  * @param {Object|String} params Name of the polymorphic relation or params
@@ -436,15 +455,7 @@ function polymorphicParams(params) {
 RelationDefinition.hasMany = function hasMany(modelFrom, modelTo, params) {
   var thisClassName = modelFrom.modelName;
   params = params || {};
-  if (typeof modelTo === 'string') {
-    params.as = modelTo;
-    if (params.model) {
-      modelTo = params.model;
-    } else {
-      var modelToName = i8n.singularize(modelTo).toLowerCase();
-      modelTo = lookupModel(modelFrom.dataSource.modelBuilder.models, modelToName);
-    }
-  }
+  modelTo = lookupModelTo(modelFrom, modelTo, params, true);
   
   var relationName = params.as || i8n.camelize(modelTo.pluralModelName, true);
   var fk = params.foreignKey || i8n.camelize(thisClassName + '_id', true);
@@ -953,13 +964,7 @@ RelationDefinition.belongsTo = function (modelFrom, modelTo, params) {
   var discriminator, polymorphic;
   params = params || {};
   if ('string' === typeof modelTo && !params.polymorphic) {
-    params.as = modelTo;
-    if (params.model) {
-      modelTo = params.model;
-    } else {
-      var modelToName = modelTo.toLowerCase();
-      modelTo = lookupModel(modelFrom.dataSource.modelBuilder.models, modelToName);
-    }
+    modelTo = lookupModelTo(modelFrom, modelTo, params);
   }
 
   var idName, relationName, fk;
@@ -1182,19 +1187,9 @@ BelongsTo.prototype.related = function (refresh, params) {
  */
 RelationDefinition.hasAndBelongsToMany = function hasAndBelongsToMany(modelFrom, modelTo, params) {
   params = params || {};
+  modelTo = lookupModelTo(modelFrom, modelTo, params, true);
+  
   var models = modelFrom.dataSource.modelBuilder.models;
-
-  if ('string' === typeof modelTo) {
-    params.as = modelTo;
-    if (params.model) {
-      modelTo = params.model;
-    } else {
-      modelTo = lookupModel(models, i8n.singularize(modelTo)) || modelTo;
-    }
-    if (typeof modelTo === 'string') {
-      throw new Error('Could not find "' + modelTo + '" relation for ' + modelFrom.modelName);
-    }
-  }
   
   if (!params.through) {
     if (params.polymorphic) throw new Error('Polymorphic relations need a through model');
@@ -1243,15 +1238,7 @@ RelationDefinition.hasAndBelongsToMany = function hasAndBelongsToMany(modelFrom,
  */
 RelationDefinition.hasOne = function (modelFrom, modelTo, params) {
   params = params || {};
-  if ('string' === typeof modelTo) {
-    params.as = modelTo;
-    if (params.model) {
-      modelTo = params.model;
-    } else {
-      var modelToName = modelTo.toLowerCase();
-      modelTo = lookupModel(modelFrom.dataSource.modelBuilder.models, modelToName);
-    }
-  }
+  modelTo = lookupModelTo(modelFrom, modelTo, params);
 
   var pk = modelFrom.dataSource.idName(modelTo.modelName) || 'id';
   var relationName = params.as || i8n.camelize(modelTo.modelName, true);
@@ -1476,18 +1463,10 @@ HasOne.prototype.related = function (refresh, params) {
 };
 
 RelationDefinition.embedsMany = function embedsMany(modelFrom, modelTo, params) {
-  var thisClassName = modelFrom.modelName;
   params = params || {};
-  if (typeof modelTo === 'string') {
-    params.as = modelTo;
-    if (params.model) {
-      modelTo = params.model;
-    } else {
-      var modelToName = i8n.singularize(modelTo).toLowerCase();
-      modelTo = lookupModel(modelFrom.dataSource.modelBuilder.models, modelToName);
-    }
-  }
+  modelTo = lookupModelTo(modelFrom, modelTo, params, true);
   
+  var thisClassName = modelFrom.modelName;
   var accessorName = params.as || (i8n.camelize(modelTo.modelName, true) + 'List');
   var relationName = params.property || i8n.camelize(modelTo.pluralModelName, true);
   var fk = modelTo.dataSource.idName(modelTo.modelName) || 'id';
@@ -1925,18 +1904,10 @@ EmbedsMany.prototype.remove = function (acInst, cb) {
 };
 
 RelationDefinition.referencesMany = function referencesMany(modelFrom, modelTo, params) {
-  var thisClassName = modelFrom.modelName;
   params = params || {};
-  if (typeof modelTo === 'string') {
-    params.as = modelTo;
-    if (params.model) {
-      modelTo = params.model;
-    } else {
-      var modelToName = i8n.singularize(modelTo).toLowerCase();
-      modelTo = lookupModel(modelFrom.dataSource.modelBuilder.models, modelToName);
-    }
-  }
+  modelTo = lookupModelTo(modelFrom, modelTo, params, true);
   
+  var thisClassName = modelFrom.modelName;
   var relationName = params.as || i8n.camelize(modelTo.pluralModelName, true);
   var fk = params.foreignKey || i8n.camelize(modelTo.modelName + '_ids', true);
   var idName = modelTo.dataSource.idName(modelTo.modelName) || 'id';