Index: kernel/Makefile
===================================================================
--- kernel/Makefile	(revision c12f8911dc227a24b5ab11008009157569740d86)
+++ kernel/Makefile	(revision f5c03a89553e2d38dd4d8cd1f1d5a961d680d3b3)
@@ -105,8 +105,7 @@
 CLANG_CFLAGS = $(INCLUDES_FLAGS) -O$(OPTIMIZATION) -imacros $(CONFIG_HEADER) \
 	-ffreestanding -fno-builtin -nostdlib -nostdinc \
-	-Wall -Werror -Wextra -Wno-unused-parameter -Wmissing-prototypes \
+	-std=gnu99 -Wall -Werror -Wextra -Wno-unused-parameter -Wmissing-prototypes \
 	-Werror-implicit-function-declaration -Wwrite-strings \
-	-integrated-as \
-	-pipe -target $(CLANG_TARGET)
+	-integrated-as -pipe -target $(CLANG_TARGET)
 
 ifeq ($(CONFIG_DEBUG),y)