diff --git a/Network/HTTP/Types.hs b/Network/HTTP/Types.hs
--- a/Network/HTTP/Types.hs
+++ b/Network/HTTP/Types.hs
@@ -300,8 +300,7 @@
 renderQueryBuilder :: Bool -- ^ prepend a question mark?
                    -> Query
                    -> A.AsciiBuilder
-renderQueryBuilder False [] = mempty
-renderQueryBuilder True [] = A.unsafeFromBuilder $ Blaze.copyByteString "?"
+renderQueryBuilder _ [] = mempty
 -- FIXME replace mconcat + map with foldr
 renderQueryBuilder qmark' (p:ps) = mconcat
     $ go (if qmark' then qmark else mempty) p
diff --git a/http-types.cabal b/http-types.cabal
--- a/http-types.cabal
+++ b/http-types.cabal
@@ -7,7 +7,7 @@
 -- The package version. See the Haskell package versioning policy
 -- (http://www.haskell.org/haskellwiki/Package_versioning_policy) for
 -- standards guiding when and how versions should be incremented.
-Version:             0.5.2
+Version:             0.5.3
 
 -- A short (one-line) description of the package.
 Synopsis:            Generic HTTP types for Haskell (for both client and server code).
diff --git a/runtests.hs b/runtests.hs
--- a/runtests.hs
+++ b/runtests.hs
@@ -2,15 +2,16 @@
 {-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
-import Debug.Trace
-import Test.Hspec
-import Test.Hspec.QuickCheck
-import Test.QuickCheck (Arbitrary (..))
-import qualified Data.Ascii               as A
-import Network.HTTP.Types
-import           Data.Text                   (Text)
-import qualified Data.ByteString as S
-import qualified Data.Text as T
+import           Data.Text             (Text)
+import           Debug.Trace
+import           Network.HTTP.Types
+import           Test.Hspec
+import           Test.Hspec.QuickCheck
+import           Test.QuickCheck       (Arbitrary (..))
+import qualified Data.Ascii            as A
+import qualified Data.ByteString       as S
+import qualified Data.ByteString.Char8 as S8
+import qualified Data.Text             as T
 
 main :: IO ()
 main = hspec $ descriptions
@@ -21,6 +22,8 @@
     , describe "encode/decode query"
         [ it "is identity to encode and then decode"
             $ property propEncodeDecodeQuery
+        , it "add ? in front of Query if and only if necessary"
+            $ property propQueryQuestionMark
         ]
     , describe "encode/decode path segments"
         [ it "is identity to encode and then decode"
@@ -44,6 +47,18 @@
   where
     q = filter (\(x, _) -> not (S.null x)) q'
 
+propQueryQuestionMark :: (Bool, Query) -> Bool
+propQueryQuestionMark (useQuestionMark, query) = actual == expected
+    where
+      actual = case S8.uncons . A.toByteString $ renderQuery useQuestionMark query of
+                 Nothing       -> False
+                 Just ('?', _) -> True
+                 _             -> False
+      expected = case (useQuestionMark, null query) of
+                   (False, _)    -> False
+                   (True, True)  -> False
+                   (True, False) -> True
+          
 propEncodeDecodePathSegments :: [Text] -> Bool
 propEncodeDecodePathSegments p' =
     p == decodePathSegments (A.toByteString $ A.fromAsciiBuilder $ encodePathSegments p)