diff --git a/lib/mongoid/grid_fs.rb b/lib/mongoid/grid_fs.rb
index 60ed44a..cff0e49 100644
--- a/lib/mongoid/grid_fs.rb
+++ b/lib/mongoid/grid_fs.rb
@@ -170,7 +170,7 @@ def put(readable, attributes = {})
           end
 
           def binary_for(*buf)
-            if defined?(Moped::BSON)
+            if defined?(Moped::BSON::Binary)
               Moped::BSON::Binary.new(:generic, buf.join)
             else
               BSON::Binary.new(buf.join, :generic)
@@ -428,7 +428,7 @@ def GridFs.build_chunk_model_for(namespace)
           self.store_in :collection => "#{ prefix }.chunks"
 
           field(:n, :type => Integer, :default => 0)
-          field(:data, :type => (defined?(Moped::BSON) ? Moped::BSON::Binary : BSON::Binary))
+          field(:data, :type => (defined?(Moped::BSON::Binary) ? Moped::BSON::Binary : BSON::Binary))
 
           belongs_to(:file, :foreign_key => :files_id, :class_name => file_model_name)
 
diff --git a/test/mongoid-grid_fs_test.rb b/test/mongoid-grid_fs_test.rb
index 593e95a..ddf1516 100644
--- a/test/mongoid-grid_fs_test.rb
+++ b/test/mongoid-grid_fs_test.rb
@@ -241,7 +241,7 @@
 
 protected
   def object_id_re
-    object_id = defined?(Moped::BSON) ? Moped::BSON::ObjectId.new : BSON::ObjectId.new
+    object_id = defined?(Moped::BSON::ObjectId) ? Moped::BSON::ObjectId.new : BSON::ObjectId.new
 
     %r| \w{#{ object_id.to_s.size }} |iomx
   end