diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1877372..ccca22b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,9 +8,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Rename `url` to `icon` in `PublicKeyCredentialRpEntity` and ignore its
   content ([#9][])
 - Truncate overlong `name` and `displayName` values for `PublicKeyCredentialEntity` instances ([#30][])
+- Send empty response to clientPin instead of empty map ([#13][])
 
 [#9]: https://github.com/solokeys/ctap-types/issues/9
 [#30]: https://github.com/solokeys/fido-authenticator/issues/30
+[#13]: https://github.com/solokeys/ctap-types/issues/13
 
 ## [0.1.2] - 2022-03-07
 
diff --git a/src/ctap2.rs b/src/ctap2.rs
index 0301bac..87a98c5 100644
--- a/src/ctap2.rs
+++ b/src/ctap2.rs
@@ -148,7 +148,13 @@ impl Response {
         let outcome = match self {
             GetInfo(response) => cbor_serialize(response, data),
             MakeCredential(response) => cbor_serialize(response, data),
-            ClientPin(response) => cbor_serialize(response, data),
+            ClientPin(response) => {
+                if response.is_empty() {
+                    Ok([].as_slice())
+                } else {
+                    cbor_serialize(response, data)
+                }
+            },
             GetAssertion(response) | GetNextAssertion(response) => cbor_serialize(response, data),
             CredentialManagement(response) => cbor_serialize(response, data),
             Reset | Selection | Vendor => Ok([].as_slice()),
diff --git a/src/ctap2/client_pin.rs b/src/ctap2/client_pin.rs
index b74c3b4..22bdf3a 100644
--- a/src/ctap2/client_pin.rs
+++ b/src/ctap2/client_pin.rs
@@ -73,6 +73,12 @@ pub struct Response {
     pub retries: Option<u8>,
 }
 
+impl Response {
+    pub fn is_empty(&self) -> bool {
+        self.key_agreement.is_none() && self.pin_token.is_none() && self.retries.is_none()
+    }
+}
+
 #[cfg(test)]
 mod tests {