diff --git a/lib/relation-definition.js b/lib/relation-definition.js
index 3f7d4477..5ab62a55 100644
--- a/lib/relation-definition.js
+++ b/lib/relation-definition.js
@@ -574,6 +574,21 @@ HasMany.prototype.destroyById = function (fkId, cb) {
   });
 };
 
+var throughKeys = function(definition) {
+  var modelThrough = definition.modelThrough;
+  var pk2 = definition.modelTo.definition.idName();
+  
+  if (definition.typeTo) { // polymorphic
+    var fk1 = definition.keyTo;
+    var fk2 = definition.keyThrough;
+  } else {
+    var fk1 = findBelongsTo(modelThrough, definition.modelFrom,
+      definition.keyFrom);
+    var fk2 = findBelongsTo(modelThrough, definition.modelTo, pk2);
+  }
+  return [fk1, fk2];
+}
+
 /**
  * Find a related item by foreign key
  * @param {*} fkId The foreign key value
@@ -664,14 +679,9 @@ HasManyThrough.prototype.create = function create(data, done) {
     // The primary key for the target model
     var pk2 = definition.modelTo.definition.idName();
     
-    if (definition.typeTo) { // polymorphic
-      var fk1 = definition.keyTo;
-      var fk2 = definition.keyThrough;
-    } else {
-      var fk1 = findBelongsTo(modelThrough, definition.modelFrom,
-        definition.keyFrom);
-      var fk2 = findBelongsTo(modelThrough, definition.modelTo, pk2);
-    }
+    var keys = throughKeys(definition);
+    var fk1 = keys[0];
+    var fk2 = keys[1];
     
     var d = {};
     d[fk1] = modelInstance[definition.keyFrom];
@@ -694,6 +704,8 @@ HasManyThrough.prototype.create = function create(data, done) {
   });
 };
 
+
+
 /**
  * Add the target model instance to the 'hasMany' relation
  * @param {Object|ID} acInst The actual instance or id value
@@ -706,14 +718,13 @@ HasManyThrough.prototype.add = function (acInst, done) {
 
   var data = {};
   var query = {};
-
-  var fk1 = findBelongsTo(modelThrough, definition.modelFrom,
-    definition.keyFrom);
-
+  
   // The primary key for the target model
   var pk2 = definition.modelTo.definition.idName();
 
-  var fk2 = findBelongsTo(modelThrough, definition.modelTo, pk2);
+  var keys = throughKeys(definition);
+  var fk1 = keys[0];
+  var fk2 = keys[1];
   
   query[fk1] = this.modelInstance[pk1];
   query[fk2] = (acInst instanceof definition.modelTo) ? acInst[pk2] : acInst;
@@ -724,6 +735,7 @@ HasManyThrough.prototype.add = function (acInst, done) {
 
   data[fk1] = this.modelInstance[pk1];
   data[fk2] = (acInst instanceof definition.modelTo) ? acInst[pk2] : acInst;
+  
   definition.applyProperties(this.modelInstance, data);
 
   // Create an instance of the through model
@@ -749,15 +761,12 @@ HasManyThrough.prototype.exists = function (acInst, done) {
   var data = {};
   var query = {};
 
-  var fk1 = findBelongsTo(modelThrough, definition.modelFrom,
-    definition.keyFrom);
-
   // The primary key for the target model
   var pk2 = definition.modelTo.definition.idName();
-
-  var fk2 = findBelongsTo(modelThrough, definition.modelTo, pk2);
-
-  query[fk1] = this.modelInstance[pk1];
+  
+  var keys = throughKeys(definition);
+  var fk1 = keys[0];
+  var fk2 = keys[1];
 
   query[fk2] = (acInst instanceof definition.modelTo) ? acInst[pk2] : acInst;
 
@@ -781,13 +790,12 @@ HasManyThrough.prototype.remove = function (acInst, done) {
 
   var query = {};
 
-  var fk1 = findBelongsTo(modelThrough, definition.modelFrom,
-    definition.keyFrom);
-
   // The primary key for the target model
   var pk2 = definition.modelTo.definition.idName();
-
-  var fk2 = findBelongsTo(modelThrough, definition.modelTo, pk2);
+  
+  var keys = throughKeys(definition);
+  var fk1 = keys[0];
+  var fk2 = keys[1];
 
   query[fk1] = this.modelInstance[pk1];
   query[fk2] = (acInst instanceof definition.modelTo) ? acInst[pk2] : acInst;
@@ -795,7 +803,7 @@ HasManyThrough.prototype.remove = function (acInst, done) {
   var filter = { where: query };
   
   definition.applyScope(this.modelInstance, filter);
-
+  
   modelThrough.deleteAll(filter.where, function (err) {
     if (!err) {
       self.removeFromCache(query[fk2]);
diff --git a/test/relations.test.js b/test/relations.test.js
index 824d710f..fe2751d6 100644
--- a/test/relations.test.js
+++ b/test/relations.test.js
@@ -792,7 +792,7 @@ describe('relations', function () {
     });
     
     it('should create polymorphic relation - author', function (done) {
-      Author.create({ id: 3, name: 'Author 1' }, function (err, author) {
+      Author.create({ id: 4, name: 'Author 1' }, function (err, author) {
         author.pictures.create({ name: 'Author Pic 1' }, function (err, p) {
           should.not.exist(err);
           p.id.should.equal(1);
@@ -819,14 +819,14 @@ describe('relations', function () {
       PictureLink.findOne(function(err, link) {
         should.not.exist(err);
         link.pictureId.should.equal(1);
-        link.imageableId.should.equal(3);
+        link.imageableId.should.equal(4);
         link.imageableType.should.equal('Author');
         done();
       });
     });
     
     it('should get polymorphic relation through model - author', function (done) {
-      Author.findById(3, function(err, author) {
+      Author.findById(4, function(err, author) {
         should.not.exist(err);
         author.name.should.equal('Author 1');
         author.pictures(function(err, pics) {
@@ -851,6 +851,68 @@ describe('relations', function () {
         });
       });
     });
+    
+    it('should include polymorphic items', function (done) {
+      Author.find({ include: 'pictures' }, function(err, authors) {
+        authors.should.have.length(1);
+        authors[0].pictures(function(err, pics) {
+          pics[0].name.should.equal('Author Pic 1');
+          pics[1].name.should.equal('Author Pic 2');
+          done();
+        });
+      });
+    });
+    
+    it('should add to a polymorphic relation - author', function (done) {
+      Author.findById(4, function(err, author) {
+        Picture.create({ id: 7, name: 'Example' }, function(err, p) {
+          author.pictures.add(p, function(err, link) {
+            link.should.be.instanceof(PictureLink);
+            link.pictureId.should.equal(7);
+            link.imageableId.should.equal(4);
+            link.imageableType.should.equal('Author');
+            done();
+          });
+        });
+      });
+    });
+    
+    it('should create polymorphic through model', function (done) {
+      PictureLink.findOne({ where: { pictureId: 7 } }, function(err, link) {
+        should.not.exist(err);
+        link.pictureId.should.equal(7);
+        link.imageableId.should.equal(4);
+        link.imageableType.should.equal('Author');
+        done();
+      });
+    });
+    
+    it('should check if polymorphic relation exists - author', function (done) {
+      Author.findById(4, function(err, author) {
+        author.pictures.exists(7, function(err, exists) {
+          exists.should.be.true;
+          done();
+        });
+      });
+    });
+    
+    it('should remove from a polymorphic relation - author', function (done) {
+      Author.findById(4, function(err, author) {
+        author.pictures.remove(7, function(err) {
+          should.not.exist(err);
+          done();
+        });
+      });
+    });
+    
+    it('should check if polymorphic relation exists - author', function (done) {
+      Author.findById(4, function(err, author) {
+        author.pictures.exists(7, function(err, exists) {
+          exists.should.be.false;
+          done();
+        });
+      });
+    });
   
   });