diff --git a/mk/validate-settings.mk b/mk/validate-settings.mk
index 351ea836b9a21b34a8a9a2d4038bda3380f23891..7c75bd408f73a4ce1dbca1818587341fab81b56f 100644
--- a/mk/validate-settings.mk
+++ b/mk/validate-settings.mk
@@ -31,10 +31,10 @@ SRC_CC_WARNING_OPTS += -Wno-unknown-pragmas
 endif
 
 SRC_CC_OPTS     += $(WERROR) -Wall
-SRC_HC_OPTS     += $(WERROR) -Wall
-
+SRC_HC_OPTS     += -Wall
 GhcStage1HcOpts += -fwarn-tabs
-GhcStage2HcOpts += -fwarn-tabs
+GhcStage2HcOpts += -fwarn-tabs $(WERROR)
+GhcLibHcOpts    += $(WERROR)
 
 utils/hpc_dist-install_EXTRA_HC_OPTS += -fwarn-tabs