diff --git a/lib/mongo/collection.rb b/lib/mongo/collection.rb
index 1a9c632..bbc5b72 100644
--- a/lib/mongo/collection.rb
+++ b/lib/mongo/collection.rb
@@ -323,8 +323,8 @@ module Mongo
     #   The _id of the inserted document or a list of _ids of all inserted documents.
     # @return [[ObjectId, Array], [Hash, Array]]
     #   1st, the _id of the inserted document or a list of _ids of all inserted documents.
-    #   2nd, a list of invalid documents as a BSON.
-    #   Return this result format when :collect_on_error is true.
+    #   2nd, a list of invalid documents.
+    #   Return this result format only when :collect_on_error is true.
     #
     # @option opts [Boolean, Hash] :safe (+false+)
     #   run the operation in safe mode, which run a getlasterror command on the
@@ -343,7 +343,7 @@ module Mongo
     #   enabled, any error will raise an OperationFailure exception.
     #   MongoDB v2.0+.
     # @option opts [Boolean] :collect_on_error (+false+) if true, then
-    #   collects invalid documents as a BSON. This option changes result format.
+    #   collects invalid documents as an array. Note that this option changes the result format.
     #
     # @core insert insert-instance_method
     def insert(doc_or_docs, opts={})
diff --git a/test/collection_test.rb b/test/collection_test.rb
index 948131d..88acfaf 100644
--- a/test/collection_test.rb
+++ b/test/collection_test.rb
@@ -152,7 +152,6 @@ class TestCollection < Test::Unit::TestCase
   end
 
   def test_bulk_insert
-    @@test.remove
     docs = []
     docs << {:foo => 1}
     docs << {:foo => 2}
@@ -161,7 +160,6 @@ class TestCollection < Test::Unit::TestCase
     assert_equal 3, response.length
     assert response.all? {|id| id.is_a?(BSON::ObjectId)}
     assert_equal 3, @@test.count
-    @@test.remove
   end
 
   def test_bulk_insert_with_continue_on_error
@@ -193,6 +191,15 @@ class TestCollection < Test::Unit::TestCase
     end
   end
 
+  def test_bson_valid_with_collect_on_error
+    docs = []
+    docs << {:foo => 1}
+    docs << {:bar => 1}
+    doc_ids, error_docs = @@test.insert(docs, :collect_on_error => true)
+    assert_equal 2, @@test.count
+    assert_equal error_docs, []
+  end
+
   def test_bson_invalid_key_serialize_error_with_collect_on_error
     docs = []
     docs << {:foo => 1}