diff --git a/Cargo.toml b/Cargo.toml
index 3ee9fdb..8207774 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -53,6 +53,10 @@ p384 = { version = "0.13", default-features = false, features = [
   "hash2curve",
   "voprf",
 ] }
+p521 = { version = "0.13", default-features = false, features = [
+  "hash2curve",
+  "voprf",
+] }
 proptest = "1"
 rand = "0.8"
 regex = "1"
@@ -63,3 +67,6 @@ sha2 = "0.10"
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
 targets = []
+
+[patch.crates-io]
+p521 = { git = "https://github.com/khonsulabs/elliptic-curves", branch = "p521-hash2curve" }
diff --git a/src/group/tests.rs b/src/group/tests.rs
index a453593..58737ce 100644
--- a/src/group/tests.rs
+++ b/src/group/tests.rs
@@ -17,6 +17,7 @@ use crate::{Error, Group, Result};
 fn test_group_properties() -> Result<()> {
     use p256::NistP256;
     use p384::NistP384;
+    use p521::NistP521;
 
     #[cfg(feature = "ristretto255")]
     {
@@ -32,6 +33,9 @@ fn test_group_properties() -> Result<()> {
     test_identity_element_error::<NistP384>()?;
     test_zero_scalar_error::<NistP384>()?;
 
+    test_identity_element_error::<NistP521>()?;
+    test_zero_scalar_error::<NistP521>()?;
+
     Ok(())
 }
 
diff --git a/src/oprf.rs b/src/oprf.rs
index 092b1c4..710b748 100644
--- a/src/oprf.rs
+++ b/src/oprf.rs
@@ -427,6 +427,7 @@ mod tests {
     fn test_functionality() -> Result<()> {
         use p256::NistP256;
         use p384::NistP384;
+        use p521::NistP521;
 
         #[cfg(feature = "ristretto255")]
         {
@@ -454,6 +455,13 @@ mod tests {
         zeroize_oprf_client::<NistP384>();
         zeroize_oprf_server::<NistP384>();
 
+        base_retrieval::<NistP521>();
+        base_inversion_unsalted::<NistP521>();
+        server_evaluate::<NistP521>();
+
+        zeroize_oprf_client::<NistP521>();
+        zeroize_oprf_server::<NistP521>();
+
         Ok(())
     }
 }
diff --git a/src/poprf.rs b/src/poprf.rs
index b2acd18..a0fd531 100644
--- a/src/poprf.rs
+++ b/src/poprf.rs
@@ -967,6 +967,7 @@ mod tests {
     fn test_functionality() -> Result<()> {
         use p256::NistP256;
         use p384::NistP384;
+        use p521::NistP521;
 
         #[cfg(feature = "ristretto255")]
         {
@@ -994,6 +995,13 @@ mod tests {
         zeroize_verifiable_client::<NistP384>();
         zeroize_verifiable_server::<NistP384>();
 
+        verifiable_retrieval::<NistP521>();
+        verifiable_bad_public_key::<NistP521>();
+        verifiable_server_evaluate::<NistP521>();
+
+        zeroize_verifiable_client::<NistP521>();
+        zeroize_verifiable_server::<NistP521>();
+
         Ok(())
     }
 }
diff --git a/src/serialization.rs b/src/serialization.rs
index a2bb6c2..a4dacd3 100644
--- a/src/serialization.rs
+++ b/src/serialization.rs
@@ -391,6 +391,7 @@ mod test {
 
             let _ = $item::<p256::NistP256>::deserialize(&$bytes[..]);
             let _ = $item::<p384::NistP384>::deserialize(&$bytes[..]);
+            let _ = $item::<p521::NistP521>::deserialize(&$bytes[..]);
         };
     }
 
diff --git a/src/tests/test_cfrg_vectors.rs b/src/tests/test_cfrg_vectors.rs
index aa31239..47c2b3a 100644
--- a/src/tests/test_cfrg_vectors.rs
+++ b/src/tests/test_cfrg_vectors.rs
@@ -89,6 +89,7 @@ macro_rules! json_to_test_vectors {
 fn test_vectors() -> Result<()> {
     use p256::NistP256;
     use p384::NistP384;
+    use p521::NistP521;
 
     let rfc: Value = serde_json::from_str(rfc_to_json(super::cfrg_vectors::VECTORS).as_str())
         .expect("Could not parse json");
@@ -188,6 +189,33 @@ fn test_vectors() -> Result<()> {
     test_poprf_finalize::<NistP384>(&p384_poprf_tvs)?;
     test_poprf_evaluate::<NistP384>(&p384_poprf_tvs)?;
 
+    let p521_oprf_tvs =
+        json_to_test_vectors!(rfc, String::from("P521-SHA512"), String::from("OPRF"));
+    assert_ne!(p521_oprf_tvs.len(), 0);
+    test_oprf_seed_to_key::<NistP521>(&p521_oprf_tvs)?;
+    test_oprf_blind::<NistP521>(&p521_oprf_tvs)?;
+    test_oprf_blind_evaluate::<NistP521>(&p521_oprf_tvs)?;
+    test_oprf_finalize::<NistP521>(&p521_oprf_tvs)?;
+    test_oprf_evaluate::<NistP521>(&p521_oprf_tvs)?;
+
+    let p521_voprf_tvs =
+        json_to_test_vectors!(rfc, String::from("P521-SHA512"), String::from("VOPRF"));
+    assert_ne!(p521_voprf_tvs.len(), 0);
+    test_voprf_seed_to_key::<NistP521>(&p521_voprf_tvs)?;
+    test_voprf_blind::<NistP521>(&p521_voprf_tvs)?;
+    test_voprf_blind_evaluate::<NistP521>(&p521_voprf_tvs)?;
+    test_voprf_finalize::<NistP521>(&p521_voprf_tvs)?;
+    test_voprf_evaluate::<NistP521>(&p521_voprf_tvs)?;
+
+    let p521_poprf_tvs =
+        json_to_test_vectors!(rfc, String::from("P521-SHA512"), String::from("POPRF"));
+    assert_ne!(p521_poprf_tvs.len(), 0);
+    test_poprf_seed_to_key::<NistP521>(&p521_poprf_tvs)?;
+    test_poprf_blind::<NistP521>(&p521_poprf_tvs)?;
+    test_poprf_blind_evaluate::<NistP521>(&p521_poprf_tvs)?;
+    test_poprf_finalize::<NistP521>(&p521_poprf_tvs)?;
+    test_poprf_evaluate::<NistP521>(&p521_poprf_tvs)?;
+
     Ok(())
 }
 
diff --git a/src/voprf.rs b/src/voprf.rs
index 4b37000..9871952 100644
--- a/src/voprf.rs
+++ b/src/voprf.rs
@@ -836,6 +836,7 @@ mod tests {
     fn test_functionality() -> Result<()> {
         use p256::NistP256;
         use p384::NistP384;
+        use p521::NistP521;
 
         #[cfg(feature = "ristretto255")]
         {
@@ -869,6 +870,15 @@ mod tests {
         zeroize_voprf_client::<NistP384>();
         zeroize_voprf_server::<NistP384>();
 
+        verifiable_retrieval::<NistP521>();
+        verifiable_batch_retrieval::<NistP521>();
+        verifiable_bad_public_key::<NistP521>();
+        verifiable_batch_bad_public_key::<NistP521>();
+        verifiable_server_evaluate::<NistP521>();
+
+        zeroize_voprf_client::<NistP521>();
+        zeroize_voprf_server::<NistP521>();
+
         Ok(())
     }
 }