Index: kernel/Makefile
===================================================================
--- kernel/Makefile	(revision b2e121ad525328882607c97cdba1a9ded6137d13)
+++ kernel/Makefile	(revision 50206e9574b78ae79eedeb03577fe6a9f9bb4d09)
@@ -90,5 +90,5 @@
 
 COMMON_CFLAGS = $(INCLUDES_FLAGS) -O$(OPTIMIZATION) -imacros $(CONFIG_HEADER) \
-	-ffreestanding -fno-builtin -nostdlib -nostdinc \
+	-ffreestanding -nostdlib -nostdinc \
 	-fexec-charset=UTF-8 -finput-charset=UTF-8 -fno-common \
 	-fdebug-prefix-map=$(realpath $(ROOT_PATH))=.