diff --git a/tests/coordinator/src/tests/batch.rs b/tests/coordinator/src/tests/batch.rs
index ea41807cc..caa567333 100644
--- a/tests/coordinator/src/tests/batch.rs
+++ b/tests/coordinator/src/tests/batch.rs
@@ -29,6 +29,7 @@ use crate::{*, tests::*};
 
 pub async fn batch(
   processors: &mut [Processor],
+  processor_is: &[u8],
   substrate_key: &Zeroizing<<Ristretto as Ciphersuite>::F>,
   batch: Batch,
 ) -> u64 {
@@ -59,7 +60,7 @@ pub async fn batch(
       .send_message(messages::coordinator::ProcessorMessage::BatchPreprocess {
         id: id.clone(),
         block: batch.block,
-        preprocess: [u8::try_from(i).unwrap(); 64].to_vec(),
+        preprocess: [processor_is[i]; 64].to_vec(),
       })
       .await;
   }
@@ -73,7 +74,7 @@ pub async fn batch(
     .send_message(messages::coordinator::ProcessorMessage::BatchPreprocess {
       id: id.clone(),
       block: batch.block,
-      preprocess: [u8::try_from(excluded_signer).unwrap(); 64].to_vec(),
+      preprocess: [processor_is[excluded_signer]; 64].to_vec(),
     })
     .await;
 
@@ -86,36 +87,32 @@ pub async fn batch(
     ) => {
       assert_eq!(&id, &this_id);
       assert_eq!(preprocesses.len(), THRESHOLD - 1);
-      assert!(!preprocesses
-        .contains_key(&Participant::new(u16::try_from(known_signer).unwrap() + 1).unwrap()));
+      let known_signer_i = Participant::new(u16::from(processor_is[known_signer])).unwrap();
+      assert!(!preprocesses.contains_key(&known_signer_i));
 
-      let mut participants =
-        preprocesses.keys().map(|p| usize::from(u16::from(*p)) - 1).collect::<HashSet<_>>();
+      let mut participants = preprocesses.keys().cloned().collect::<HashSet<_>>();
       for (p, preprocess) in preprocesses {
-        assert_eq!(preprocess, vec![u8::try_from(u16::from(p)).unwrap() - 1; 64]);
+        assert_eq!(preprocess, vec![u8::try_from(u16::from(p)).unwrap(); 64]);
       }
-      participants.insert(known_signer);
+      participants.insert(known_signer_i);
       participants
     }
     _ => panic!("coordinator didn't send back BatchPreprocesses"),
   };
 
   for i in participants.clone() {
-    if i == known_signer {
+    if u16::from(i) == u16::from(processor_is[known_signer]) {
       continue;
     }
-    let processor = &mut processors[i];
+
+    let processor =
+      &mut processors[processor_is.iter().position(|p_i| u16::from(*p_i) == u16::from(i)).unwrap()];
     let mut preprocesses = participants
       .clone()
       .into_iter()
-      .map(|i| {
-        (
-          Participant::new(u16::try_from(i + 1).unwrap()).unwrap(),
-          [u8::try_from(i).unwrap(); 64].to_vec(),
-        )
-      })
+      .map(|i| (i, [u8::try_from(u16::from(i)).unwrap(); 64].to_vec()))
       .collect::<HashMap<_, _>>();
-    preprocesses.remove(&Participant::new(u16::try_from(i + 1).unwrap()).unwrap());
+    preprocesses.remove(&i);
 
     assert_eq!(
       processor.recv_message().await,
@@ -129,25 +126,25 @@ pub async fn batch(
   }
 
   for i in participants.clone() {
-    let processor = &mut processors[i];
+    let processor =
+      &mut processors[processor_is.iter().position(|p_i| u16::from(*p_i) == u16::from(i)).unwrap()];
     processor
       .send_message(messages::coordinator::ProcessorMessage::BatchShare {
         id: id.clone(),
-        share: [u8::try_from(i).unwrap(); 32],
+        share: [u8::try_from(u16::from(i)).unwrap(); 32],
       })
       .await;
   }
   wait_for_tributary().await;
   for i in participants.clone() {
-    let processor = &mut processors[i];
+    let processor =
+      &mut processors[processor_is.iter().position(|p_i| u16::from(*p_i) == u16::from(i)).unwrap()];
     let mut shares = participants
       .clone()
       .into_iter()
-      .map(|i| {
-        (Participant::new(u16::try_from(i + 1).unwrap()).unwrap(), [u8::try_from(i).unwrap(); 32])
-      })
+      .map(|i| (i, [u8::try_from(u16::from(i)).unwrap(); 32]))
       .collect::<HashMap<_, _>>();
-    shares.remove(&Participant::new(u16::try_from(i + 1).unwrap()).unwrap());
+    shares.remove(&i);
 
     assert_eq!(
       processor.recv_message().await,
@@ -271,9 +268,10 @@ async fn batch_test() {
       }
       let mut processors = new_processors;
 
-      let (substrate_key, _) = key_gen::<Secp256k1>(&mut processors).await;
+      let (processor_is, substrate_key, _) = key_gen::<Secp256k1>(&mut processors).await;
       batch(
         &mut processors,
+        &processor_is,
         &substrate_key,
         Batch {
           network: NetworkId::Bitcoin,
diff --git a/tests/coordinator/src/tests/key_gen.rs b/tests/coordinator/src/tests/key_gen.rs
index a13a9dd03..81a6aa15f 100644
--- a/tests/coordinator/src/tests/key_gen.rs
+++ b/tests/coordinator/src/tests/key_gen.rs
@@ -11,7 +11,7 @@ use ciphersuite::{
   group::{ff::Field, GroupEncoding},
   Ciphersuite, Ristretto, Secp256k1,
 };
-use dkg::{Participant, ThresholdParams};
+use dkg::ThresholdParams;
 
 use serai_client::{
   primitives::NetworkId,
@@ -24,21 +24,32 @@ use crate::{*, tests::*};
 
 pub async fn key_gen<C: Ciphersuite>(
   processors: &mut [Processor],
-) -> (Zeroizing<<Ristretto as Ciphersuite>::F>, Zeroizing<C::F>) {
-  let participant_from_i = |i: usize| Participant::new(u16::try_from(i + 1).unwrap()).unwrap();
+) -> (Vec<u8>, Zeroizing<<Ristretto as Ciphersuite>::F>, Zeroizing<C::F>) {
+  let mut participant_is = vec![];
 
   let set = ValidatorSet { session: Session(0), network: NetworkId::Bitcoin };
   let id = KeyGenId { set, attempt: 0 };
 
   for (i, processor) in processors.iter_mut().enumerate() {
+    let msg = processor.recv_message().await;
+    match &msg {
+      CoordinatorMessage::KeyGen(messages::key_gen::CoordinatorMessage::GenerateKey {
+        params,
+        ..
+      }) => {
+        participant_is.push(params.i());
+      }
+      _ => panic!("unexpected message: {msg:?}"),
+    }
+
     assert_eq!(
-      processor.recv_message().await,
+      msg,
       CoordinatorMessage::KeyGen(messages::key_gen::CoordinatorMessage::GenerateKey {
         id,
         params: ThresholdParams::new(
           u16::try_from(((COORDINATORS * 2) / 3) + 1).unwrap(),
           u16::try_from(COORDINATORS).unwrap(),
-          participant_from_i(i),
+          participant_is[i],
         )
         .unwrap()
       })
@@ -47,7 +58,7 @@ pub async fn key_gen<C: Ciphersuite>(
     processor
       .send_message(messages::key_gen::ProcessorMessage::Commitments {
         id,
-        commitments: vec![u8::try_from(i).unwrap()],
+        commitments: vec![u8::try_from(u16::from(participant_is[i])).unwrap()],
       })
       .await;
   }
@@ -55,9 +66,14 @@ pub async fn key_gen<C: Ciphersuite>(
   wait_for_tributary().await;
   for (i, processor) in processors.iter_mut().enumerate() {
     let mut commitments = (0 .. u8::try_from(COORDINATORS).unwrap())
-      .map(|l| (participant_from_i(l.into()), vec![l]))
+      .map(|l| {
+        (
+          participant_is[usize::from(l)],
+          vec![u8::try_from(u16::from(participant_is[usize::from(l)])).unwrap()],
+        )
+      })
       .collect::<HashMap<_, _>>();
-    commitments.remove(&participant_from_i(i));
+    commitments.remove(&participant_is[i]);
     assert_eq!(
       processor.recv_message().await,
       CoordinatorMessage::KeyGen(messages::key_gen::CoordinatorMessage::Commitments {
@@ -66,13 +82,20 @@ pub async fn key_gen<C: Ciphersuite>(
       })
     );
 
-    // from (0 .. n), to (1 ..= n)
+    // Recipient it's for -> (Sender i, Recipient i)
     let mut shares = (0 .. u8::try_from(COORDINATORS).unwrap())
-      .map(|l| (participant_from_i(l.into()), vec![u8::try_from(i).unwrap(), l + 1]))
+      .map(|l| {
+        (
+          participant_is[usize::from(l)],
+          vec![
+            u8::try_from(u16::try_from(participant_is[i]).unwrap()).unwrap(),
+            u8::try_from(u16::from(participant_is[usize::from(l)])).unwrap(),
+          ],
+        )
+      })
       .collect::<HashMap<_, _>>();
 
-    let i = participant_from_i(i);
-    shares.remove(&i);
+    shares.remove(&participant_is[i]);
     processor.send_message(messages::key_gen::ProcessorMessage::Shares { id, shares }).await;
   }
 
@@ -87,14 +110,22 @@ pub async fn key_gen<C: Ciphersuite>(
 
   wait_for_tributary().await;
   for (i, processor) in processors.iter_mut().enumerate() {
-    let i = participant_from_i(i);
+    let i = participant_is[i];
     assert_eq!(
       processor.recv_message().await,
       CoordinatorMessage::KeyGen(messages::key_gen::CoordinatorMessage::Shares {
         id,
         shares: {
           let mut shares = (0 .. u8::try_from(COORDINATORS).unwrap())
-            .map(|l| (participant_from_i(l.into()), vec![l, u8::try_from(u16::from(i)).unwrap()]))
+            .map(|l| {
+              (
+                participant_is[usize::from(l)],
+                vec![
+                  u8::try_from(u16::from(participant_is[usize::from(l)])).unwrap(),
+                  u8::try_from(u16::from(i)).unwrap(),
+                ],
+              )
+            })
             .collect::<HashMap<_, _>>();
           shares.remove(&i);
           shares
@@ -172,7 +203,11 @@ pub async fn key_gen<C: Ciphersuite>(
     (Public(substrate_key), network_key.try_into().unwrap())
   );
 
-  (substrate_priv_key, network_priv_key)
+  (
+    participant_is.into_iter().map(|i| u8::try_from(u16::from(i)).unwrap()).collect(),
+    substrate_priv_key,
+    network_priv_key,
+  )
 }
 
 #[tokio::test]
diff --git a/tests/coordinator/src/tests/sign.rs b/tests/coordinator/src/tests/sign.rs
index 1a835b205..4c9903386 100644
--- a/tests/coordinator/src/tests/sign.rs
+++ b/tests/coordinator/src/tests/sign.rs
@@ -29,6 +29,7 @@ use crate::{*, tests::*};
 
 pub async fn sign<C: Ciphersuite>(
   processors: &mut [Processor],
+  processor_is: &[u8],
   network_key: &Zeroizing<C::F>,
   plan_id: [u8; 32],
 ) {
@@ -50,7 +51,7 @@ pub async fn sign<C: Ciphersuite>(
     processor
       .send_message(messages::sign::ProcessorMessage::Preprocess {
         id: id.clone(),
-        preprocess: [u8::try_from(i).unwrap(); 64].to_vec(),
+        preprocess: [processor_is[i]; 64].to_vec(),
       })
       .await;
   }
@@ -63,7 +64,7 @@ pub async fn sign<C: Ciphersuite>(
   processors[excluded_signer]
     .send_message(messages::sign::ProcessorMessage::Preprocess {
       id: id.clone(),
-      preprocess: [u8::try_from(excluded_signer).unwrap(); 64].to_vec(),
+      preprocess: [processor_is[excluded_signer]; 64].to_vec(),
     })
     .await;
 
@@ -76,37 +77,32 @@ pub async fn sign<C: Ciphersuite>(
     }) => {
       assert_eq!(&id, &this_id);
       assert_eq!(preprocesses.len(), THRESHOLD - 1);
-      assert!(!preprocesses
-        .contains_key(&Participant::new(u16::try_from(known_signer).unwrap() + 1).unwrap()));
+      let known_signer_i = Participant::new(u16::from(processor_is[known_signer])).unwrap();
+      assert!(!preprocesses.contains_key(&known_signer_i));
 
-      let mut participants =
-        preprocesses.keys().map(|p| usize::from(u16::from(*p)) - 1).collect::<HashSet<_>>();
+      let mut participants = preprocesses.keys().cloned().collect::<HashSet<_>>();
       for (p, preprocess) in preprocesses {
-        assert_eq!(preprocess, vec![u8::try_from(u16::from(p)).unwrap() - 1; 64]);
+        assert_eq!(preprocess, vec![u8::try_from(u16::from(p)).unwrap(); 64]);
       }
-      participants.insert(known_signer);
+      participants.insert(known_signer_i);
       participants
     }
     _ => panic!("coordinator didn't send back Preprocesses"),
   };
 
   for i in participants.clone() {
-    if i == known_signer {
+    if u16::from(i) == u16::from(processor_is[known_signer]) {
       continue;
     }
 
-    let processor = &mut processors[i];
+    let processor =
+      &mut processors[processor_is.iter().position(|p_i| u16::from(*p_i) == u16::from(i)).unwrap()];
     let mut preprocesses = participants
       .clone()
       .into_iter()
-      .map(|i| {
-        (
-          Participant::new(u16::try_from(i + 1).unwrap()).unwrap(),
-          [u8::try_from(i).unwrap(); 64].to_vec(),
-        )
-      })
+      .map(|i| (i, [u8::try_from(u16::from(i)).unwrap(); 64].to_vec()))
       .collect::<HashMap<_, _>>();
-    preprocesses.remove(&Participant::new(u16::try_from(i + 1).unwrap()).unwrap());
+    preprocesses.remove(&i);
 
     assert_eq!(
       processor.recv_message().await,
@@ -118,28 +114,25 @@ pub async fn sign<C: Ciphersuite>(
   }
 
   for i in participants.clone() {
-    let processor = &mut processors[i];
+    let processor =
+      &mut processors[processor_is.iter().position(|p_i| u16::from(*p_i) == u16::from(i)).unwrap()];
     processor
       .send_message(messages::sign::ProcessorMessage::Share {
         id: id.clone(),
-        share: vec![u8::try_from(i).unwrap(); 32],
+        share: vec![u8::try_from(u16::from(i)).unwrap(); 32],
       })
       .await;
   }
   wait_for_tributary().await;
   for i in participants.clone() {
-    let processor = &mut processors[i];
+    let processor =
+      &mut processors[processor_is.iter().position(|p_i| u16::from(*p_i) == u16::from(i)).unwrap()];
     let mut shares = participants
       .clone()
       .into_iter()
-      .map(|i| {
-        (
-          Participant::new(u16::try_from(i + 1).unwrap()).unwrap(),
-          vec![u8::try_from(i).unwrap(); 32],
-        )
-      })
+      .map(|i| (i, vec![u8::try_from(u16::from(i)).unwrap(); 32]))
       .collect::<HashMap<_, _>>();
-    shares.remove(&Participant::new(u16::try_from(i + 1).unwrap()).unwrap());
+    shares.remove(&i);
 
     assert_eq!(
       processor.recv_message().await,
@@ -152,7 +145,8 @@ pub async fn sign<C: Ciphersuite>(
 
   // Send Completed
   for i in participants.clone() {
-    let processor = &mut processors[i];
+    let processor =
+      &mut processors[processor_is.iter().position(|p_i| u16::from(*p_i) == u16::from(i)).unwrap()];
     processor
       .send_message(messages::sign::ProcessorMessage::Completed {
         key: id.key.clone(),
@@ -199,7 +193,8 @@ async fn sign_test() {
       }
       let mut processors = new_processors;
 
-      let (substrate_key, network_key) = key_gen::<Secp256k1>(&mut processors).await;
+      let (participant_is, substrate_key, network_key) =
+        key_gen::<Secp256k1>(&mut processors).await;
 
       // 'Send' external coins into Serai
       let serai = processors[0].serai().await;
@@ -234,6 +229,7 @@ async fn sign_test() {
       let coin_block = BlockHash([0x33; 32]);
       let block_included_in = batch(
         &mut processors,
+        &participant_is,
         &substrate_key,
         Batch {
           network: NetworkId::Bitcoin,
@@ -366,7 +362,7 @@ async fn sign_test() {
           .await;
       }
 
-      sign::<Secp256k1>(&mut processors, &network_key, plan_id).await;
+      sign::<Secp256k1>(&mut processors, &participant_is, &network_key, plan_id).await;
     })
     .await;
 }