diff --git a/compos/common/lib.rs b/compos/common/lib.rs
index 6e397a2..9a4d0e3 100644
--- a/compos/common/lib.rs
+++ b/compos/common/lib.rs
@@ -55,6 +55,9 @@
 /// The file that holds the instance image for a CompOS instance.
 pub const INSTANCE_IMAGE_FILE: &str = "instance.img";
 
+/// The file that holds the idsig for the CompOS Payload APK.
+pub const IDSIG_FILE: &str = "idsig";
+
 /// The path within our config APK of our default VM configuration file, used at boot time.
 pub const DEFAULT_VM_CONFIG_PATH: &str = "assets/vm_config.json";