diff --git a/build.rs b/build.rs
index 83302a6..fd9a91c 100644
--- a/build.rs
+++ b/build.rs
@@ -1,4 +1,9 @@
 fn main() {
+    // define LBOS_FONT
+    if std::env::var("LBOS_FONT").is_err() {
+        println!("cargo:rustc-env=LBOS_FONT=charset1.data");
+    }
+
     let arch = std::env::var("LBOS_ARCH").unwrap_or("virt".to_string());
     println!("cargo:rerun-if-env-changed=LBOS_ARCH");
     println!("cargo:rerun-if-env-changed=LBOS_FONT");