diff --git a/avr-atmega328p.json b/avr-atmega328p.json
index e2d266c..0f0306b 100644
--- a/avr-atmega328p.json
+++ b/avr-atmega328p.json
@@ -15,6 +15,7 @@
   "linker-flavor": "gcc",
   "linker-is-gnu": true,
   "llvm-target": "avr-unknown-unknown",
+  "no-builtins": true,
   "max-atomic-width": 8,
   "no-default-libraries": false,
   "pre-link-args": {