diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index ed11560..0fa8221 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -10,14 +10,23 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: build disk image
       run: make image.bin
   llvm:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install lld
       run: sudo apt-get install -y lld
     - name: LLVM build
       run: make LLVM=on image.bin
+  macos:
+    runs-on: macos-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: install llvm
+      run: brew install llvm x86_64-elf-binutils x86_64-elf-gcc
+    - name: LLVM build
+      run: make LLVM=on image.bin
+
diff --git a/Makefile b/Makefile
index ad49a62..a5eeab3 100644
--- a/Makefile
+++ b/Makefile
@@ -10,13 +10,14 @@ OBJCOPY=x86_64-elf-objcopy
 endif
 
 CFLAGS = -fno-pic -ffreestanding -static -fno-builtin -fno-strict-aliasing \
+		 -mno-sse \
 		 -Wall -ggdb -m32 -Werror -fno-omit-frame-pointer
 CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
 ASMFLAGS = -m32 -ffreestanding -c -g
 
 ifeq ($(LLVM),on)
 #AS=llvm-as
-LD=ld.lld
+LD=PATH=/usr/local/opt/llvm/bin:$(PATH) ld.lld
 CC=clang
 CFLAGS += -target elf-i386
 ASMFLAGS = -target elf-i386 -ffreestanding -c -g
@@ -33,6 +34,21 @@ run: image.bin
 run-nox: image.bin
 	qemu-system-i386 -nographic -drive format=raw,file=$< -serial mon:stdio
 
+ejudge.sh: image.bin
+	echo >$@ "#!/bin/sh"
+	echo >>$@ "base64 -d <<===EOF | gunzip >image.bin"
+	gzip <$^ | base64 >>$@
+	echo >>$@ "===EOF"
+	echo >>$@ "exec qemu-system-i386 -nographic -drive format=raw,file=image.bin -serial mon:stdio"
+	chmod +x $@
+
+diag:
+	-uname -a
+	-$(CC) --version
+	-$(LD) -v
+	-gcc --version
+	-ld -v
+
 debug-boot-nox: image.bin mbr.elf
 	qemu-system-i386 -nographic -drive format=raw,file=$< -s -S &
 	$(GDB) mbr.elf \