Index: ghc6-6.12.1/configure
===================================================================
--- ghc6-6.12.1.orig/configure	2009-12-10 18:31:41.000000000 +0000
+++ ghc6-6.12.1/configure	2010-12-09 15:37:29.544743681 +0000
@@ -2661,7 +2661,7 @@
   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
 
