diff --git a/repak/src/footer.rs b/repak/src/footer.rs
index 2539760..c8746f8 100644
--- a/repak/src/footer.rs
+++ b/repak/src/footer.rs
@@ -81,6 +81,9 @@ impl Footer {
         writer.write_u64::<LE>(self.index_offset)?;
         writer.write_u64::<LE>(self.index_size)?;
         writer.write_all(&self.hash)?;
+        if self.version_major == VersionMajor::FrozenIndex {
+            writer.write_bool(self.frozen)?;
+        }
         let algo_size = match self.version {
             ver if ver < Version::V8A => 0,
             ver if ver < Version::V8B => 4,