diff --git a/Makefile b/Makefile
index db99120a77..c19d83e58e 100644
--- a/Makefile
+++ b/Makefile
@@ -15,9 +15,11 @@ FFI_TEST_CFLAGS = -fPIC
 ifdef DEBUG
 	CFLAGS += -g
 else
-	CFLAGS += -O3 $(SITE_CFLAGS)
+	CFLAGS += -O3
 endif
 
+CFLAGS += $(SITE_CFLAGS)
+
 ENGINE = $(DLL_PREFIX)factor$(DLL_SUFFIX)$(DLL_EXTENSION)
 
 ifdef CONFIG