diff --git a/matchbox_protocol/src/lib.rs b/matchbox_protocol/src/lib.rs
index 9bf180df..30e14def 100644
--- a/matchbox_protocol/src/lib.rs
+++ b/matchbox_protocol/src/lib.rs
@@ -39,7 +39,7 @@ cfg_if! {
 
         impl fmt::Display for JsonPeerRequest {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                write!(f, "{}", serde_json::to_string(self).expect("error serializing message"))
+                write!(f, "{}", serde_json::to_string(self).map_err(|_| fmt::Error)?)
             }
         }
         impl std::str::FromStr for JsonPeerRequest {
@@ -52,7 +52,7 @@ cfg_if! {
 
         impl fmt::Display for JsonPeerEvent {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                write!(f, "{}", serde_json::to_string(self).expect("error serializing message"))
+                write!(f, "{}", serde_json::to_string(self).map_err(|_| fmt::Error)?)
             }
         }
         impl std::str::FromStr for JsonPeerEvent {