--- mozilla/js/src/configure.in.orig	2012-03-12 10:27:55.000000000 +0100
+++ mozilla/js/src/configure.in	2012-03-12 10:28:22.000000000 +0100
@@ -2831,12 +2831,14 @@
     AC_DEFINE(JS_NUNBOX32)
     ;;
 sparc*-*)
+    if test ! "$HAVE_64BIT_OS" ; then
     ENABLE_METHODJIT=1
     ENABLE_MONOIC=1
     ENABLE_POLYIC=1
     ENABLE_METHODJIT_TYPED_ARRAY=1
     AC_DEFINE(JS_CPU_SPARC)
     AC_DEFINE(JS_NUNBOX32)
+    fi
     ;;
 esac