diff --git a/lib/mongo/util/bson.rb b/lib/mongo/util/bson.rb
index 6a96206..a7afaa0 100644
--- a/lib/mongo/util/bson.rb
+++ b/lib/mongo/util/bson.rb
@@ -47,6 +47,7 @@ class BSON
   CODE_W_SCOPE = 15
   NUMBER_INT = 16
   TIMESTAMP = 17
+  NUMBER_LONG = 18
   MAXKEY = 127
 
   if RUBY_VERSION >= '1.9'
@@ -180,6 +181,9 @@ class BSON
         when NUMBER_INT
           key = deserialize_cstr(@buf)
           doc[key] = deserialize_number_int_data(@buf)
+        when NUMBER_LONG
+          key = deserialize_cstr(@buf)
+          doc[key] = deserialize_number_long_data(@buf)
         when OID
           key = deserialize_cstr(@buf)
           doc[key] = deserialize_oid_data(@buf)
@@ -263,6 +267,12 @@ class BSON
     unsigned >= 2**32 / 2 ? unsigned - 2**32 : unsigned
   end
 
+  def deserialize_number_long_data(buf)
+    # same note as above applies here...
+    unsigned = buf.get_long
+    unsigned >= 2 ** 64 / 2 ? unsigned - 2**64 : unsigned
+  end
+
   def deserialize_object_data(buf)
     size = buf.get_int
     buf.position -= 4
@@ -394,15 +404,23 @@ class BSON
   end
 
   def serialize_number_element(buf, key, val, type)
-    buf.put(type)
-    self.class.serialize_cstr(buf, key)
     if type == NUMBER
+      buf.put(type)
+      self.class.serialize_cstr(buf, key)
       buf.put_double(val)
     else
-      if val > 2**32 / 2 - 1 or val < -2**32 / 2
-        raise RangeError.new("MongoDB can only handle 4-byte ints - try converting to a double before saving")
+      if val > 2**64 / 2 - 1 or val < -2**64 / 2
+        raise RangeError.new("MongoDB can only handle 8-byte ints")
+      end
+      if val > 2**32 / 2 - 1 or val < -2**32 / 2
+        buf.put(NUMBER_LONG)
+        self.class.serialize_cstr(buf, key)
+        buf.put_long(val)
+      else
+        buf.put(type)
+        self.class.serialize_cstr(buf, key)
+        buf.put_int(val)
       end
-      buf.put_int(val)
     end
   end
 
diff --git a/tests/test_bson.rb b/tests/test_bson.rb
index e63fc5b..8651ca3 100644
--- a/tests/test_bson.rb
+++ b/tests/test_bson.rb
@@ -215,18 +215,32 @@ class BSONTest < Test::Unit::TestCase
   end
 
   def test_overflow
-    doc = {"x" => 2**45}
+    doc = {"x" => 2**75}
     assert_raise RangeError do
       @b.serialize(doc)
     end
 
-    doc = {"x" => 2147483647}
+    doc = {"x" => 9223372036854775}
+    assert_equal doc, @b.deserialize(@b.serialize(doc).to_a)
+
+    doc = {"x" => 9223372036854775807}
     assert_equal doc, @b.deserialize(@b.serialize(doc).to_a)
 
     doc["x"] = doc["x"] + 1
     assert_raise RangeError do
       @b.serialize(doc)
     end
+
+    doc = {"x" => -9223372036854775}
+    assert_equal doc, @b.deserialize(@b.serialize(doc).to_a)
+
+    doc = {"x" => -9223372036854775808}
+    assert_equal doc, @b.deserialize(@b.serialize(doc).to_a)
+
+    doc["x"] = doc["x"] - 1
+    assert_raise RangeError do
+      @b.serialize(doc)
+    end
   end
 
   def test_do_not_change_original_object
diff --git a/tests/test_db_api.rb b/tests/test_db_api.rb
index 044e8a2..e1b7715 100644
--- a/tests/test_db_api.rb
+++ b/tests/test_db_api.rb
@@ -639,6 +639,12 @@ class DBAPITest < Test::Unit::TestCase
     assert_equal 2, @@coll.count
   end
 
+  def test_save_long
+    @@coll.clear
+    @@coll.insert("x" => 9223372036854775807)
+    assert_equal 9223372036854775807, @@coll.find_first()["x"]
+  end
+
   def test_find_by_oid
     @@coll.clear