diff --git a/zebrad/src/components/sync.rs b/zebrad/src/components/sync.rs
index a9362d6a6..d6a26c59d 100644
--- a/zebrad/src/components/sync.rs
+++ b/zebrad/src/components/sync.rs
@@ -97,6 +97,9 @@ const TIPS_RETRY_TIMEOUT: Duration = Duration::from_secs(60);
 /// networks, and on testnet, which has a small number of slow peers.
 const SYNC_RESTART_TIMEOUT: Duration = Duration::from_secs(100);
 
+type BoxError = Box<dyn std::error::Error + Send + Sync + 'static>;
+type ReportAndHash = (Report, block::Hash);
+
 /// Helps work around defects in the bitcoin protocol by checking whether
 /// the returned hashes actually extend a chain tip.
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
@@ -108,11 +111,11 @@ struct CheckedTip {
 #[derive(Debug)]
 pub struct ChainSync<ZN, ZS, ZV>
 where
-    ZN: Service<zn::Request, Response = zn::Response, Error = Error> + Send + Clone + 'static,
+    ZN: Service<zn::Request, Response = zn::Response, Error = BoxError> + Send + Clone + 'static,
     ZN::Future: Send,
-    ZS: Service<zs::Request, Response = zs::Response, Error = Error> + Send + Clone + 'static,
+    ZS: Service<zs::Request, Response = zs::Response, Error = BoxError> + Send + Clone + 'static,
     ZS::Future: Send,
-    ZV: Service<Arc<Block>, Response = block::Hash, Error = Error> + Send + Clone + 'static,
+    ZV: Service<Arc<Block>, Response = block::Hash, Error = BoxError> + Send + Clone + 'static,
     ZV::Future: Send,
 {
     /// Used to perform ObtainTips and ExtendTips requests, with no retry logic
@@ -135,11 +138,11 @@ where
 /// diffusion.
 impl<ZN, ZS, ZV> ChainSync<ZN, ZS, ZV>
 where
-    ZN: Service<zn::Request, Response = zn::Response, Error = Error> + Send + Clone + 'static,
+    ZN: Service<zn::Request, Response = zn::Response, Error = BoxError> + Send + Clone + 'static,
     ZN::Future: Send,
-    ZS: Service<zs::Request, Response = zs::Response, Error = Error> + Send + Clone + 'static,
+    ZS: Service<zs::Request, Response = zs::Response, Error = BoxError> + Send + Clone + 'static,
     ZS::Future: Send,
-    ZV: Service<Arc<Block>, Response = block::Hash, Error = Error> + Send + Clone + 'static,
+    ZV: Service<Arc<Block>, Response = block::Hash, Error = BoxError> + Send + Clone + 'static,
     ZV::Future: Send,
 {
     /// Returns a new syncer instance, using:
@@ -676,9 +679,6 @@ where
     }
 }
 
-type Error = Box<dyn std::error::Error + Send + Sync + 'static>;
-type ReportAndHash = (Report, block::Hash);
-
 #[cfg(test)]
 mod test {
     use super::*;