diff --git a/mk/config.mk.in b/mk/config.mk.in
index fb9f40fae1f87fbe062a5ed3130d36288549b573..7c1e262f7644e2477e1f181aca9e7ce29ffb37e5 100644
--- a/mk/config.mk.in
+++ b/mk/config.mk.in
@@ -610,6 +610,10 @@ ifeq "$(HAPPY)" ""
 HAPPY			= $(HAPPY_PREFIX)happy
 endif
 
+ifeq ($(Ghc2_0),NO)
+SRC_HAPPY_OPTS		= -1.2
+endif
+
 #
 # Stuff from fptools/literate
 #