diff --git a/amazonka-core.cabal b/amazonka-core.cabal
--- a/amazonka-core.cabal
+++ b/amazonka-core.cabal
@@ -1,5 +1,5 @@
 name:                  amazonka-core
-version:               1.3.3
+version:               1.3.3.1
 synopsis:              Core data types and functionality for Amazonka libraries.
 homepage:              https://github.com/brendanhay/amazonka
 bug-reports:           https://github.com/brendanhay/amazonka/issues
diff --git a/src/Network/AWS/Data/Headers.hs b/src/Network/AWS/Data/Headers.hs
--- a/src/Network/AWS/Data/Headers.hs
+++ b/src/Network/AWS/Data/Headers.hs
@@ -74,6 +74,9 @@
 hHost :: HeaderName
 hHost = "Host"
 
+hExpect :: HeaderName
+hExpect = "Expect"
+
 hAMZToken :: HeaderName
 hAMZToken = "X-Amz-Security-Token"
 
@@ -118,9 +121,6 @@
 
 hTransferEncoding :: HeaderName
 hTransferEncoding = "Transfer-Encoding"
-
-hExpect :: HeaderName
-hExpect = "Expect"
 
 hFormEncoded :: ByteString
 hFormEncoded = "application/x-www-form-urlencoded; charset=utf-8"
diff --git a/src/Network/AWS/Sign/V4/Base.hs b/src/Network/AWS/Sign/V4/Base.hs
--- a/src/Network/AWS/Sign/V4/Base.hs
+++ b/src/Network/AWS/Sign/V4/Base.hs
@@ -41,7 +41,7 @@
 import           Network.AWS.Request
 import           Network.AWS.Types
 import qualified Network.HTTP.Conduit        as Client
-import           Network.HTTP.Types.Header
+import qualified Network.HTTP.Types.Header   as H
 
 import           Prelude
 
@@ -88,7 +88,7 @@
      -> (V4, ClientRequest -> ClientRequest)
 base h rq a r ts = (meta, auth)
   where
-    auth = requestHeaders <>~ [(hAuthorization, authorisation meta)]
+    auth = requestHeaders <>~ [(H.hAuthorization, authorisation meta)]
 
     meta = signMetadata a r ts presigner h (prepare rq)