--- ghc6-6.12.1.orig/configure
+++ ghc6-6.12.1/configure
@@ -2661,7 +2661,7 @@ if test ! -f utils/ghc-pwd/ghc-pwd && te
   rm -f *.hi
   rm -f ghc-pwd
   rm -f ghc-pwd.exe
-  "$WithGhc" -v0 --make ghc-pwd -o ghc-pwd
+  "$WithGhc" -v0 -optl-pthread --make ghc-pwd -o ghc-pwd
   cd ../..
 fi
 
