diff --git a/boot1/build.rs b/boot1/build.rs
index 72ddaad..f226a46 100644
--- a/boot1/build.rs
+++ b/boot1/build.rs
@@ -36,7 +36,7 @@ fn build_asm(nasm: &Nasm, out_dir: &Path) {
   nasm.assemble(
     &out_dir.join("prelude.bin"),
     &["asm/prelude.s".as_ref()],
-    &["..".as_ref()],
+    &["../include".as_ref()],
   ).unwrap();
 }
 
diff --git a/defines.s b/include/defines.s
similarity index 100%
rename from defines.s
rename to include/defines.s
diff --git a/justfile b/justfile
index b2f64df..871e12c 100644
--- a/justfile
+++ b/justfile
@@ -6,8 +6,8 @@ run:
     -drive format=raw,file=disk.bin
 
 build:
-  nasm -f bin -o boot0.bin boot0.s
-  nasm -f bin -o boot1.bin boot1.s
+  nasm -f bin -Iinclude -o boot0.bin boot0.s
+  nasm -f bin -Iinclude -o boot1.bin boot1.s
 
 zero_disk:
   dd if=/dev/zero of=disk.bin bs=512 count=1000