diff --git a/crates/ruma-events/src/reaction.rs b/crates/ruma-events/src/reaction.rs
index 5c26b30e..66b2d570 100644
--- a/crates/ruma-events/src/reaction.rs
+++ b/crates/ruma-events/src/reaction.rs
@@ -43,6 +43,7 @@ pub struct Relation {
     pub event_id: EventId,
 
     /// A string that holds the emoji reaction.
+    #[serde(rename = "key")]
     pub emoji: String,
 }