diff --git a/plume-common/src/activity_pub/request.rs b/plume-common/src/activity_pub/request.rs
index 29201180..35bc0059 100644
--- a/plume-common/src/activity_pub/request.rs
+++ b/plume-common/src/activity_pub/request.rs
@@ -9,6 +9,9 @@ use crate::activity_pub::{ap_accept_header, AP_CONTENT_TYPE};
 
 const PLUME_USER_AGENT: &str = concat!("Plume/", env!("CARGO_PKG_VERSION"));
 
+#[derive(Debug)]
+pub struct Error();
+
 pub struct Digest(String);
 
 impl Digest {
@@ -61,16 +64,16 @@ impl Digest {
         base64::decode(&self.0[pos..]).expect("Digest::value: invalid encoding error")
     }
 
-    pub fn from_header(dig: &str) -> Result<Self, ()> {
+    pub fn from_header(dig: &str) -> Result<Self, Error> {
         if let Some(pos) = dig.find('=') {
             let pos = pos + 1;
             if base64::decode(&dig[pos..]).is_ok() {
                 Ok(Digest(dig.to_owned()))
             } else {
-                Err(())
+                Err(Error())
             }
         } else {
-            Err(())
+            Err(Error())
         }
     }
 
@@ -109,7 +112,7 @@ pub fn headers() -> HeaderMap {
     headers
 }
 
-pub fn signature<S: Signer>(signer: &S, headers: &HeaderMap) -> Result<HeaderValue, ()> {
+pub fn signature<S: Signer>(signer: &S, headers: &HeaderMap) -> Result<HeaderValue, Error> {
     let signed_string = headers
         .iter()
         .map(|(h, v)| {
@@ -129,7 +132,7 @@ pub fn signature<S: Signer>(signer: &S, headers: &HeaderMap) -> Result<HeaderVal
         .join(" ")
         .to_lowercase();
 
-    let data = signer.sign(&signed_string).map_err(|_| ())?;
+    let data = signer.sign(&signed_string).map_err(|_| Error())?;
     let sign = base64::encode(&data);
 
     HeaderValue::from_str(&format!(
@@ -137,5 +140,5 @@ pub fn signature<S: Signer>(signer: &S, headers: &HeaderMap) -> Result<HeaderVal
         key_id = signer.get_key_id(),
         signed_headers = signed_headers,
         signature = sign
-    )).map_err(|_| ())
+    )).map_err(|_| Error())
 }
diff --git a/plume-common/src/activity_pub/sign.rs b/plume-common/src/activity_pub/sign.rs
index 496d4c6d..a6bb5899 100644
--- a/plume-common/src/activity_pub/sign.rs
+++ b/plume-common/src/activity_pub/sign.rs
@@ -17,6 +17,9 @@ pub fn gen_keypair() -> (Vec<u8>, Vec<u8>) {
     )
 }
 
+#[derive(Debug)]
+pub struct Error();
+
 pub trait Signer {
     type Error;
 
@@ -29,7 +32,7 @@ pub trait Signer {
 }
 
 pub trait Signable {
-    fn sign<T>(&mut self, creator: &T) -> Result<&mut Self, ()>
+    fn sign<T>(&mut self, creator: &T) -> Result<&mut Self, Error>
     where
         T: Signer;
     fn verify<T>(self, creator: &T) -> bool
@@ -43,7 +46,7 @@ pub trait Signable {
 }
 
 impl Signable for serde_json::Value {
-    fn sign<T: Signer>(&mut self, creator: &T) -> Result<&mut serde_json::Value, ()> {
+    fn sign<T: Signer>(&mut self, creator: &T) -> Result<&mut serde_json::Value, Error> {
         let creation_date = Utc::now().to_rfc3339();
         let mut options = json!({
             "type": "RsaSignature2017",
@@ -61,7 +64,7 @@ impl Signable for serde_json::Value {
         let document_hash = Self::hash(&self.to_string());
         let to_be_signed = options_hash + &document_hash;
 
-        let signature = base64::encode(&creator.sign(&to_be_signed).map_err(|_| ())?);
+        let signature = base64::encode(&creator.sign(&to_be_signed).map_err(|_| Error())?);
 
         options["signatureValue"] = serde_json::Value::String(signature);
         self["signature"] = options;