diff --git a/matrix_sdk_crypto/src/verification/mod.rs b/matrix_sdk_crypto/src/verification/mod.rs
index 2d9bd37f..adb6f63c 100644
--- a/matrix_sdk_crypto/src/verification/mod.rs
+++ b/matrix_sdk_crypto/src/verification/mod.rs
@@ -122,7 +122,7 @@ impl Cancelled {
             }
             CancelCode::User => "The user cancelled the verification.",
             CancelCode::UserMismatch => "The expected user did not match the verified user",
-            _ => unimplemented!(),
+            _ => "Unknown cancel reason",
         };
 
         Self { cancel_code: code, reason }