diff --git a/cabal-install/src/Distribution/Client/SetupWrapper.hs b/cabal-install/src/Distribution/Client/SetupWrapper.hs
index 1b401ff6f7c..f0f977b9101 100644
--- a/cabal-install/src/Distribution/Client/SetupWrapper.hs
+++ b/cabal-install/src/Distribution/Client/SetupWrapper.hs
@@ -1070,7 +1070,10 @@ getExternalSetupMethod verbosity options pkg bt = do
               (program, extraOpts) =
                 case compilerFlavor compiler of
                   GHCJS -> (ghcjsProgram, ["-build-runner"])
-                  _ -> (ghcProgram, ["-threaded"])
+                  _ -> (ghcProgram, [])
+                    -- FIXME: don't enable -threaded unconditionnally: we may
+                    -- only have vanilla libraries (but maybe we don't have them
+                    -- either?)
               cabalDep =
                 maybe
                   []