diff --git a/crates/s3/src/select.rs b/crates/s3/src/select.rs
index d3ae504..a39d0fd 100644
--- a/crates/s3/src/select.rs
+++ b/crates/s3/src/select.rs
@@ -252,12 +252,24 @@ mod tests {
         assert!(matches!(e, Error::Auth(msg) if msg.contains("Access denied")));
     }
 
+    #[test]
+    fn classify_empty_code_maps_no_such_bucket_substring() {
+        let e = classify_aws_code(Some(""), "Service error: ... NoSuchBucket ...");
+        assert!(matches!(e, Error::NotFound(msg) if msg.contains("Bucket")));
+    }
+
     #[test]
     fn classify_empty_code_maps_no_such_key_substring() {
         let e = classify_aws_code(Some(""), "Service error: ... NoSuchKey ...");
         assert!(matches!(e, Error::NotFound(msg) if msg.contains("Object")));
     }
 
+    #[test]
+    fn classify_empty_code_maps_not_implemented_substring() {
+        let e = classify_aws_code(Some(""), "Service error: backend returned NotImplemented");
+        assert!(matches!(e, Error::UnsupportedFeature(msg) if msg.contains("does not support")));
+    }
+
     #[test]
     fn classify_maps_invalid_argument() {
         let e = classify_aws_code(Some("InvalidArgument"), "bad expr");