diff --git a/mk/suffix.mk b/mk/suffix.mk
index af86e44739909e11e0b1a147abc3a7fa0ef0d2c0..f6d4bba0dce54991af361cd5af383840d231c13c 100644
--- a/mk/suffix.mk
+++ b/mk/suffix.mk
@@ -117,7 +117,10 @@ SRC_HC_PRE_OPTS  += $(HC_PRE__)
 #
 
 %.hs : %.gc
-	$(GREENCARD) $(GREENCARD_OPTS) $<
+	$(GREENCARD) $(GREENCARD_OPTS) $< -o $@
+
+%.lhs : %.gc
+	$(GREENCARD) $(GREENCARD_OPTS) $< -o $@
 
 #-----------------------------------------------------------------------------
 # C-related suffix rules