diff --git a/Makefile b/Makefile
index 3f9e2aa..85a20a9 100644
--- a/Makefile
+++ b/Makefile
@@ -6,12 +6,29 @@ CC=gcc
 LD=ld
 LDFLAGS=-melf_i386 -Ttext 0x1000 --oformat binary
 
-basicos:
+all: os-image
+
+os-image: boot_sect.bin kernel.bin
+	mkdir -p $(BIN)
+	cat $^ > $(BIN)/$@
+
+# build kernel binary file
+kernel.bin: kernel_entry.o kernel.o
+	$(LD) $(LDFLAGS) $^ -o $@
+
+# build kernel object file
+kernel.o: kernel.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+# build kernel entry object file
+kernel_entry.o: kernel_entry.asm
+	$(ASM) -f elf $< -o $@
+
+boot_sect.bin: boot_sect.asm
+	$(ASM) $< $(AFLAGS) -o $@
+
+basicos: boot_sect.bin kernel.bin
 	mkdir -p $(BIN)
-	$(ASM) boot_sect.asm $(AFLAGS) -o boot_sect.bin
-	$(ASM) kernel_entry.asm -f elf -o kernel_entry.o
-	$(CC) $(CFLAGS) -c kernel.c -o kernel.o
-	$(LD) $(LDFLAGS) -o kernel.bin kernel_entry.o kernel.o
 	cat boot_sect.bin kernel.bin > $(BIN)/os-image