diff --git a/Makefile b/Makefile
index 824e8e1..64ccd50 100644
--- a/Makefile
+++ b/Makefile
@@ -364,7 +364,7 @@
 endif
 
 ifneq ($(USE_REGPARM),)
-OPTIONS_CFLAGS += -DCONFIG_HAP_USE_REGPARM
+OPTIONS_CFLAGS += -DCONFIG_REGPARM=3
 BUILD_OPTIONS  += $(call ignore_implicit,USE_REGPARM)
 endif