diff --git a/ghc/mk/paths.mk b/ghc/mk/paths.mk
index a6bb13e1830d897a108e62cc16ed220197a996ae..0c33928f3d131c302f4e690ec5b778c93ba64a54 100644
--- a/ghc/mk/paths.mk
+++ b/ghc/mk/paths.mk
@@ -73,3 +73,6 @@ MKDEPENDHS_SRCS = $(HS_SRCS)
 else
 MKDEPENDHS_SRCS =
 endif
+
+# temporary until the new RTS is merged in.
+MOSTLY_CLEAN_FILES += *.hc