diff --git a/src/prd.rs b/src/prd.rs
index e8f6328..18cedb0 100644
--- a/src/prd.rs
+++ b/src/prd.rs
@@ -87,7 +87,7 @@ impl Prd {
 
     pub fn new_update(
         root_commitment: OutPoint,
-        sender: String, // Should take Member as argument
+        sender: Member,
         roles: HashMap<String, RoleDefinition>,
         keys: Map<String, Value>,
         pcd_commitments: Value,
@@ -95,7 +95,7 @@ impl Prd {
         Self {
             prd_type: PrdType::Update,
             root_commitment: root_commitment.to_string(),
-            sender,
+            sender: serde_json::to_string(&sender).unwrap(),
             validation_tokens: vec![],
             keys,
             pcd_commitments,
@@ -106,14 +106,14 @@ impl Prd {
 
     pub fn new_response(
         root_commitment: OutPoint,
-        sender: String,
+        sender: Member,
         validation_tokens: Vec<Proof>,
         pcd_commitments: Value,
     ) -> Self {
         Self {
             prd_type: PrdType::Response,
             root_commitment: root_commitment.to_string(),
-            sender,
+            sender: serde_json::to_string(&sender).unwrap(),
             validation_tokens: validation_tokens,
             keys: Map::new(),
             pcd_commitments,