diff --git a/rustfs/src/storage/sse.rs b/rustfs/src/storage/sse.rs
index 87f5af497..a876783c9 100644
--- a/rustfs/src/storage/sse.rs
+++ b/rustfs/src/storage/sse.rs
@@ -4565,11 +4565,9 @@ mod tests {
         })
         .await
         .expect_err("mismatched kms context should fail");
-        assert!(
-            err.message.contains("context") || err.message.contains("Context"),
-            "unexpected error for mismatched kms context: {}",
-            err.message
-        );
+        assert_eq!(err.code, S3ErrorCode::InternalError);
+        assert_eq!(err.message, ApiError::error_code_to_message(&S3ErrorCode::InternalError));
+        assert_eq!(super::kms_data_plane_error_class(&err), "context_mismatch");
 
         manager.stop().await.expect("kms service should stop cleanly");
         reset_sse_dek_provider();