diff --git a/imagekit/models.py b/imagekit/models.py
index e1d3d95..52135fc 100755
--- a/imagekit/models.py
+++ b/imagekit/models.py
@@ -147,7 +147,8 @@ class _ImageSpecFileMixin(object):
         if getattr(self.field, 'autoconvert', True):
             autoconvert_processor = AutoConvert(format)
             img = autoconvert_processor.process(img)
-            options.update(autoconvert_processor.save_kwargs)
+            options = dict(autoconvert_processor.save_kwargs.items() + \
+                    options.items())
 
         imgfile = img_to_fobj(img, format, **options)
         content = ContentFile(imgfile.read())
diff --git a/imagekit/processors/__init__.py b/imagekit/processors/__init__.py
index f5a76f0..c7ff304 100644
--- a/imagekit/processors/__init__.py
+++ b/imagekit/processors/__init__.py
@@ -251,6 +251,6 @@ class AutoConvert(object):
             img = bg.convert('RGB')
 
         if self.format == 'JPEG':
-            self.save_kwargs.setdefault('optimize', True)
+            self.save_kwargs['optimize'] = True
 
         return img