diff --git a/Database/MongoDB/Internal/Protocol.hs b/Database/MongoDB/Internal/Protocol.hs
index 26d190c..df4e367 100644
--- a/Database/MongoDB/Internal/Protocol.hs
+++ b/Database/MongoDB/Internal/Protocol.hs
@@ -494,6 +494,9 @@ data FlagBit =
     | ExhaustAllowed  -- ^ The client is prepared for multiple replies to this request using the moreToCome bit.
     deriving (Show, Eq, Enum)
 
+uOptDoc :: UpdateOption -> Document
+uOptDoc Upsert = ["upsert" =: True]
+uOptDoc MultiUpdate = ["multi" =: True]
 
 {-
   OP_MSG header == 16 byte
@@ -528,7 +531,7 @@ putOpMsg cmd requestId flagBit params = do
                 putCString "documents"               -- identifier
                 mapM_ putDocument iDocuments         -- payload
             Update{..} -> do
-                let doc = ["q" =: uSelector, "u" =: uUpdater]
+                let doc = ["q" =: uSelector, "u" =: uUpdater] <> concatMap uOptDoc uOptions
                     (sec0, sec1Size) =
                       prepSectionInfo
                           uFullCollection
diff --git a/test/QuerySpec.hs b/test/QuerySpec.hs
index 4d7435e..e7aa1fa 100644
--- a/test/QuerySpec.hs
+++ b/test/QuerySpec.hs
@@ -4,6 +4,7 @@
 module QuerySpec (spec) where
 import Data.String (IsString(..))
 import TestImport
+import Control.Concurrent (threadDelay)
 import Control.Exception
 import Control.Monad (forM_, when)
 import System.Environment (getEnv)
@@ -87,6 +88,21 @@ spec = around withCleanDatabase $ do
       db (count $ select ["name" =: "Yankees", "league" =: "American"] "team") `shouldReturn` 1
       _id `shouldBe` ()
 
+  describe "upsert" $ do
+    it "upserts a document twice with the same spec" $ do
+      let q = select ["name" =: "jack"] "users"
+      db $ upsert q ["color" =: "blue", "name" =: "jack"]
+      -- since there is no way to ask for a ack, we must wait for "a sufficient time"
+      -- for the write to be visible
+      threadDelay 10000
+      db (rest =<< find (select [] "users")) >>= print
+      db (count $ select ["name" =: "jack"] "users") `shouldReturn` 1
+      db $ upsert q ["color" =: "red", "name" =: "jack"]
+      threadDelay 10000
+      db (count $ select ["name" =: "jack"] "users") `shouldReturn` 1
+      Just doc <- db $ findOne (select ["name" =: "jack"] "users")
+      doc !? "color" `shouldBe` Just "red"
+
   describe "insertMany" $ do
     it "inserts documents to the collection and returns their _ids" $ do
       (_id1:_id2:_) <- db $ insertMany "team" [ ["name" =: "Yankees", "league" =: "American"]