diff --git a/os/Makefile b/os/Makefile
index a7d26e7583b2627ea9669eb5ee6c463f21ef5089..b79267b4f45c48daa4704bf450c9d664d292f501 100644
--- a/os/Makefile
+++ b/os/Makefile
@@ -10,13 +10,13 @@ SDCARD := /dev/sdb
 APPS := ../user/src/bin
 
 # BOARD
-BOARD		?= qemu
-SBI			?= rustsbi
-BOOTLOADER	:= ../bootloader/$(SBI)-$(BOARD).bin
+BOARD ?= qemu
+SBI ?= rustsbi
+BOOTLOADER := ../bootloader/$(SBI)-$(BOARD).bin
 
 # Run K210
 K210-SERIALPORT	= /dev/ttyUSB0
-K210-BURNER		= ../tools/kflash.py
+K210-BURNER	= ../tools/kflash.py
 
 # Binutils
 OBJDUMP := rust-objdump --arch-name=riscv64
@@ -28,10 +28,10 @@ DISASM ?= -x
 build: env $(KERNEL_BIN) $(FS_IMG)
 
 env:
-	(rustup component list | grep "rust-src") || rustup component add rust-src
-	(rustup component list | grep "llvm-tools-preview") || rustup component add llvm-tools-preview
-	(which rust-objdump) || cargo install cargo-binutils
-	(rustup target list | grep "riscv64gc-unknown-none-elf") || rustup target add riscv64gc-unknown-none-elf
+	(rustup target list | grep "riscv64gc-unknown-none-elf (installed)") || rustup target add $(TARGET)
+	cargo install cargo-binutils
+	rustup component add rust-src
+	rustup component add llvm-tools-preview
 
 sdcard: $(FS_IMG)
 	@echo "Are you sure write to $(SDCARD) ? [y/N] " && read ans && [ $${ans:-N} = y ]
diff --git a/rust-toolchain b/rust-toolchain
index bf867e0ae5b6c08df1118a2ece970677bc479f1b..a08f00d19c20fa1348bc138d4e779060b23a6e50 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-nightly
+nightly-2021-01-30