diff --git a/src/backends/all.rs b/src/backends/all.rs
index 0d10959..57e2c6a 100644
--- a/src/backends/all.rs
+++ b/src/backends/all.rs
@@ -74,6 +74,7 @@ macro_rules! package_ids {
     ($($backend:ident),*) => {
         #[derive(Debug, Clone, Default, Serialize)]
         #[allow(non_snake_case)]
+        #[serde(rename_all = "lowercase")]
         pub struct PackageIds {
             $(
                 #[serde(skip_serializing_if = "BTreeSet::is_empty")]