diff --git a/gogol-core.cabal b/gogol-core.cabal
--- a/gogol-core.cabal
+++ b/gogol-core.cabal
@@ -1,5 +1,5 @@
 name:                  gogol-core
-version:               0.1.0
+version:               0.1.1
 synopsis:              Core data types and functionality for Gogol libraries.
 homepage:              https://github.com/brendanhay/gogol
 bug-reports:           https://github.com/brendanhay/gogol/issues
@@ -55,7 +55,7 @@
         , exceptions           >= 0.6
         , hashable             >= 1.2
         , http-api-data        >= 0.2
-        , http-client          >= 0.4.4
+        , http-client          >= 0.5 && < 1
         , http-media           >= 0.6
         , http-types           >= 0.8.6
         , lens                 >= 4.4
diff --git a/src/Network/Google/Data/Time.hs b/src/Network/Google/Data/Time.hs
--- a/src/Network/Google/Data/Time.hs
+++ b/src/Network/Google/Data/Time.hs
@@ -14,25 +14,33 @@
     ( Time'
     , Date'
     , DateTime'
+    , Duration
 
     , _Time
     , _Date
     , _DateTime
+    , _Duration
     ) where
 
 import           Control.Lens
 import           Data.Aeson
-import qualified Data.Aeson.Types     as Aeson
+import qualified Data.Aeson.Types                  as Aeson
 import           Data.Attoparsec.Text
-import           Data.Bifunctor       (first, second)
-import           Data.Bits            ((.&.))
-import           Data.Char            (ord)
-import           Data.Data            (Data, Typeable)
-import           Data.Text            (Text)
-import qualified Data.Text            as Text
+import           Data.Bifunctor                    (first, second)
+import           Data.Bits                         ((.&.))
+import           Data.Char                         (ord)
+import           Data.Data                         (Data, Typeable)
+import           Data.Scientific                   (Scientific)
+import qualified Data.Scientific                   as Sci
+import           Data.Text                         (Text)
+import qualified Data.Text                         as Text
+import qualified Data.Text.Lazy                    as LText
+import qualified Data.Text.Lazy.Builder            as Build
+import qualified Data.Text.Lazy.Builder.Scientific as Sci
 import           Data.Time
 import           GHC.Generics
-import           Web.HttpApiData      (FromHttpApiData (..), ToHttpApiData (..))
+import           Web.HttpApiData                   (FromHttpApiData (..),
+                                                    ToHttpApiData (..))
 
 -- | This SHOULD be a time in the format of hh:mm:ss.  It is
 -- recommended that you use the "date-time" format instead of "time"
@@ -66,9 +74,29 @@
 _DateTime :: Iso' DateTime' UTCTime
 _DateTime = iso unDateTime DateTime'
 
+-- | A duration in seconds with up to nine fractional digits, terminated by 's'.
+--
+-- /Example/: @"3.5s"@.
+newtype Duration = Duration { unDuration :: Scientific }
+    deriving (Eq, Ord, Show, Read, Generic, Data, Typeable)
+
+_Duration :: Iso' Duration Scientific
+_Duration = iso unDuration Duration
+
+instance ToHttpApiData Duration where
+    toQueryParam =
+          LText.toStrict
+        . Build.toLazyText
+        . Sci.formatScientificBuilder Sci.Fixed (Just 9)
+        . unDuration
+
+instance FromHttpApiData Duration where
+    parseQueryParam = second Duration . parseText durationParser
+
 instance ToJSON Time'     where toJSON = String . toQueryParam
 instance ToJSON Date'     where toJSON = String . toQueryParam
 instance ToJSON DateTime' where toJSON = toJSON . unDateTime
+instance ToJSON Duration  where toJSON = String . toQueryParam
 
 instance FromJSON Time' where
     parseJSON = fmap Time' . withText "time" (run timeParser)
@@ -79,6 +107,9 @@
 instance FromJSON DateTime' where
     parseJSON = fmap DateTime' . parseJSON
 
+instance FromJSON Duration where
+    parseJSON = fmap Duration . withText "duration" (run durationParser)
+
 parseText :: Parser a -> Text -> Either Text a
 parseText p = first Text.pack . parseOnly p
 
@@ -99,6 +130,9 @@
     m <- twoDigits <* char '-'
     d <- twoDigits
     maybe (fail "invalid date") pure (fromGregorianValid y m d)
+
+durationParser :: Parser Scientific
+durationParser = Sci.fromFloatDigits <$> (double <* char 's')
 
 -- | Parse a two-digit integer (e.g. day of month, hour).
 twoDigits :: Parser Int
diff --git a/src/Network/Google/Prelude.hs b/src/Network/Google/Prelude.hs
--- a/src/Network/Google/Prelude.hs
+++ b/src/Network/Google/Prelude.hs
@@ -13,12 +13,13 @@
 import Control.Lens        as Export (Lens', lens, mapping, ( # ), (^.), _Just)
 import Data.ByteString     as Export (ByteString)
 import Data.Data           as Export (Data, Typeable)
-import Data.Hashable       as Export
+import Data.Hashable       as Export (Hashable, hashWithSalt)
 import Data.HashMap.Strict as Export (HashMap)
 import Data.Int            as Export (Int32, Int64)
 import Data.Maybe          as Export
 import Data.Monoid         as Export (mempty, (<>))
 import Data.Proxy          as Export
+import Data.Scientific     as Export (Scientific)
 import Data.Text           as Export (Text)
 import Data.Time           as Export (Day, TimeOfDay, UTCTime)
 import Data.Word           as Export (Word32, Word64, Word8)
@@ -26,7 +27,7 @@
 import Network.HTTP.Client as Export (RequestBody)
 import Numeric.Natural     as Export (Natural)
 import Prelude             as Export hiding (product)
-import Servant.API         as Export hiding (getResponse)
+import Servant.API         as Export hiding (Headers, getResponse)
 import Servant.Utils.Links as Export hiding (Link)
 import Web.HttpApiData     as Export (FromHttpApiData (..), ToHttpApiData (..))
 
diff --git a/src/Network/Google/Types.hs b/src/Network/Google/Types.hs
--- a/src/Network/Google/Types.hs
+++ b/src/Network/Google/Types.hs
@@ -40,7 +40,7 @@
 import           Data.Data
 import           Data.DList                   (DList)
 import qualified Data.DList                   as DList
-import           Data.Foldable                (foldl')
+import           Data.Foldable                (foldMap, foldl')
 import           Data.Monoid
 import           Data.String
 import           Data.Text                    (Text)
@@ -488,7 +488,7 @@
 
     buildClient Proxy rq x = buildClient (Proxy :: Proxy fn)
         . appendPath rq
-        $ buildText x <> buildSymbol (Proxy :: Proxy m)
+        $ buildText x <> ":" <> buildSymbol (Proxy :: Proxy m)
 
 instance ( KnownSymbol   s
          , ToHttpApiData a