diff --git a/Cargo.toml b/Cargo.toml
index 62431ff..116bf5f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "prism"
-version = "0.1.0"
+version = "0.1.1"
 edition = "2021"
 license = "Apache-2.0"
 
diff --git a/src/mr.rs b/src/mr.rs
index ca74ef5..5a11dc0 100644
--- a/src/mr.rs
+++ b/src/mr.rs
@@ -59,11 +59,18 @@ struct ValueQuantity {
     value: f64,
 }
 
+#[derive(Debug, Deserialize, Serialize)]
+struct ValueRatio {
+    denominator: Value,
+    numerator: Value,
+}
+
 #[derive(Debug, Deserialize, Serialize)]
 #[serde(rename_all = "camelCase")]
 struct Extension {
     url: String,
-    value_quantity: ValueQuantity,
+    value_quantity: Option<ValueQuantity>,
+    value_ratio: Option<ValueRatio>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]