Index: boot/Makefile.build
===================================================================
--- boot/Makefile.build	(revision 09ab0a9afc9379f1604c0fd75cac2d9287ba022c)
+++ boot/Makefile.build	(revision 460ea7ed2af9977b884414b68b2f7b94fa472cfd)
@@ -40,5 +40,5 @@
 
 COMMON_CFLAGS = $(INCLUDES) -O$(OPTIMIZATION) -imacros $(CONFIG_HEADER) \
-	-ffreestanding -fno-builtin -nostdlib -nostdinc \
+	-ffreestanding -nostdlib \
 	-fexec-charset=UTF-8 -finput-charset=UTF-8 -fno-common \
 	-fdebug-prefix-map=$(realpath $(ROOT_PATH))=.