diff --git a/Makefile b/Makefile
index bbe690c..cadee98 100644
--- a/Makefile
+++ b/Makefile
@@ -1,16 +1,28 @@
-CODE=src/
-CROSS_COMPILE=riscv64-unknown-elf-
-CC=$(CROSS_COMPILE)gcc
-GDB=$(CROSS_COMPILE)gdb
-CFLAGS=-march=rv64gc -mabi=lp64d -static -mcmodel=medany -fvisibility=hidden -nostdlib -nostartfiles -Tkernel.ld -g -Wall -Wextra
-EMU=qemu-system-riscv64
-EFLAGS=-machine virt -cpu rv64 -bios opensbi-riscv64-generic-fw_dynamic.bin -m 256m -nographic -global virtio-mmio.force-legacy=false -s #-S
+TARGET = riscv64-unknown-elf
+CC     = $(TARGET)-gcc
+GDB    = $(TARGET)-gdb
+EMU    = qemu-system-riscv64
 
-.PHONY: all clean run
+CODE = src/
+
+CFLAGS = -march=rv64gc -mabi=lp64d -static -mcmodel=medany -fvisibility=hidden -nostdlib -nostartfiles -Tkernel.ld -g -Wall -Wextra
+ifeq ($(CC),clang)
+	CFLAGS += -target $(TARGET) -mno-relax -Wno-unused-command-line-argument
+endif
+
+EFLAGS = -machine virt -cpu rv64 -bios opensbi-riscv64-generic-fw_dynamic.bin -m 256m -nographic -global virtio-mmio.force-legacy=false -s
+ifdef WAIT_GDB
+	EFLAGS += -S
+endif
+
+.PHONY: all clean run gdb
 
 all: $(CODE)*.s $(CODE)*.c
 	$(CC) $(CFLAGS) $? -o kernel
-	  
+
+clean:
+	-rm kernel
+
 run:
 	$(EMU) $(EFLAGS) -kernel kernel