diff --git a/GHCApi.hs b/GHCApi.hs
index c258295..4a16ab6 100644
--- a/GHCApi.hs
+++ b/GHCApi.hs
@@ -75,7 +75,7 @@ initSession opt cmdOpts idirs mDepPkgs mLangExts logging file = do
         df1 <- modifyFlagsWithOpts df0 cmdOpts
         fast <- liftIO $ getFastCheck df0 file mLangExts
         let df2 = modifyFlags df1 idirs mDepPkgs fast (expandSplice opt)
-        df3 <- setGhcFlags df2 opt
+        df3 <- modifyFlagsWithOpts df2 $ ghcOpts opt
         liftIO $ setLogger logging df3
 
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@@ -83,12 +83,12 @@ initSession opt cmdOpts idirs mDepPkgs mLangExts logging file = do
 initializeFlags :: Options -> Ghc ()
 initializeFlags opt = do
     dflags0 <- getSessionDynFlags
-    dflags1 <- setGhcFlags dflags0 opt
+    dflags1 <- modifyFlagsWithOpts dflags0 $ ghcOpts opt
     void $ setSessionDynFlags dflags1
 
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-getHeaderExtension :: DynFlags -> FilePath -> IO [String]
+getHeaderExtension :: DynFlags -> FilePath -> IO [HeaderExt]
 getHeaderExtension dflags file = map unLoc <$> getOptionsFromFile dflags file
 
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@@ -106,13 +106,6 @@ useTemplateHaskell mLangExts hdrExts = th1 || th2
 
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-modifyFlagsWithOpts :: DynFlags -> [String] -> Ghc DynFlags
-modifyFlagsWithOpts dflags cmdOpts = do
-    (dflags',_,_) <- parseDynamicFlags dflags (map noLoc cmdOpts)
-    return dflags'
-
-----------------------------------------------------------------
-
 -- FIXME removing Options
 modifyFlags :: DynFlags -> [IncludeDir] -> Maybe [Package] -> Bool -> Bool -> DynFlags
 modifyFlags d0 idirs mDepPkgs fast splice
@@ -146,10 +139,11 @@ addDevPkgs df pkgs = df''
 
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-setGhcFlags :: Monad m => DynFlags -> Options -> m DynFlags
-setGhcFlags flagset opt =
-  do (flagset',_,_) <- parseDynamicFlags flagset (map noLoc (ghcOpts opt))
-     return flagset'
+modifyFlagsWithOpts :: DynFlags -> [String] -> Ghc DynFlags
+modifyFlagsWithOpts dflags cmdOpts =
+    tfst <$> parseDynamicFlags dflags (map noLoc cmdOpts)
+  where
+    tfst (a,_,_) = a
 
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