diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for lsp-test
 
+## 0.6.0.0 -- 2019-07-04
+
+* Update to haskell-lsp-0.15.0.0 (@lorenzo)
+
 ## 0.5.4.0 -- 2019-06-13
 
 * Fix `getDefinitions` for SingleLoc (@cocreature)
diff --git a/lsp-test.cabal b/lsp-test.cabal
--- a/lsp-test.cabal
+++ b/lsp-test.cabal
@@ -1,5 +1,5 @@
 name:                lsp-test
-version:             0.5.4.0
+version:             0.6.0.0
 synopsis:            Functional test framework for LSP servers.
 description:
   A test framework for writing tests against
@@ -36,7 +36,7 @@
                      , parser-combinators:Control.Applicative.Combinators
   default-language:    Haskell2010
   build-depends:       base >= 4.10 && < 5
-                     , haskell-lsp == 0.14.*
+                     , haskell-lsp == 0.15.*
                      , aeson
                      , aeson-pretty
                      , ansi-terminal
@@ -79,7 +79,7 @@
   build-depends:       base >= 4.10 && < 5
                      , hspec
                      , lens
-                     , haskell-lsp == 0.14.*
+                     , haskell-lsp == 0.15.*
                      , lsp-test
                      , data-default
                      , aeson
diff --git a/src/Language/Haskell/LSP/Test.hs b/src/Language/Haskell/LSP/Test.hs
--- a/src/Language/Haskell/LSP/Test.hs
+++ b/src/Language/Haskell/LSP/Test.hs
@@ -201,7 +201,7 @@
 documentContents :: TextDocumentIdentifier -> Session T.Text
 documentContents doc = do
   vfs <- vfs <$> get
-  let file = vfs Map.! (doc ^. uri)
+  let file = vfs Map.! toNormalizedUri (doc ^. uri)
   return $ Rope.toText $ Language.Haskell.LSP.VFS._text file
 
 -- | Parses an ApplyEditRequest, checks that it is for the passed document
@@ -435,7 +435,7 @@
 -- | Returns the current diagnostics that have been sent to the client.
 -- Note that this does not wait for more to come in.
 getCurrentDiagnostics :: TextDocumentIdentifier -> Session [Diagnostic]
-getCurrentDiagnostics doc = fromMaybe [] . Map.lookup (doc ^. uri) . curDiagnostics <$> get
+getCurrentDiagnostics doc = fromMaybe [] . Map.lookup (toNormalizedUri $ doc ^. uri) . curDiagnostics <$> get
 
 -- | Executes a command.
 executeCommand :: Command -> Session ()
@@ -464,7 +464,7 @@
 getVersionedDoc (TextDocumentIdentifier uri) = do
   fs <- vfs <$> get
   let ver =
-        case fs Map.!? uri of
+        case fs Map.!? toNormalizedUri uri of
           Just (VirtualFile v _ _) -> Just v
           _ -> Nothing
   return (VersionedTextDocumentIdentifier uri ver)
diff --git a/src/Language/Haskell/LSP/Test/Session.hs b/src/Language/Haskell/LSP/Test/Session.hs
--- a/src/Language/Haskell/LSP/Test/Session.hs
+++ b/src/Language/Haskell/LSP/Test/Session.hs
@@ -128,7 +128,7 @@
   {
     curReqId :: LspId
   , vfs :: VFS
-  , curDiagnostics :: Map.Map Uri [Diagnostic]
+  , curDiagnostics :: Map.Map NormalizedUri [Diagnostic]
   , curTimeoutId :: Int
   , overridingTimeout :: Bool
   -- ^ The last received message from the server.
@@ -227,7 +227,7 @@
   let List diags = n ^. params . diagnostics
       doc = n ^. params . uri
   modify (\s ->
-    let newDiags = Map.insert doc diags (curDiagnostics s)
+    let newDiags = Map.insert (toNormalizedUri doc) diags (curDiagnostics s)
       in s { curDiagnostics = newDiags })
 
 updateState (ReqApplyWorkspaceEdit r) = do
@@ -246,7 +246,7 @@
     newVFS <- liftIO $ changeFromServerVFS (vfs s) r
     return $ s { vfs = newVFS }
 
-  let groupedParams = groupBy (\a b -> (a ^. textDocument == b ^. textDocument)) allChangeParams
+  let groupedParams = groupBy (\a b -> a ^. textDocument == b ^. textDocument) allChangeParams
       mergedParams = map mergeParams groupedParams
 
   -- TODO: Don't do this when replaying a session
@@ -261,7 +261,7 @@
     modify $ \s ->
       let oldVFS = vfs s
           update (VirtualFile oldV t mf) = VirtualFile (fromMaybe oldV v) t mf
-          newVFS = Map.adjust update uri oldVFS
+          newVFS = Map.adjust update (toNormalizedUri uri) oldVFS
       in s { vfs = newVFS }
 
   where checkIfNeedsOpened uri = do
@@ -269,7 +269,7 @@
           ctx <- ask
 
           -- if its not open, open it
-          unless (uri `Map.member` oldVFS) $ do
+          unless (toNormalizedUri uri `Map.member` oldVFS) $ do
             let fp = fromJust $ uriToFilePath uri
             contents <- liftIO $ T.readFile fp
             let item = TextDocumentItem (filePathToUri fp) "" 0 contents