diff --git a/2016/tools/xlsxread/src/format_detect_2016.rs b/2016/tools/xlsxread/src/format_detect_2016.rs
index 768a88c..8103a4e 100644
--- a/2016/tools/xlsxread/src/format_detect_2016.rs
+++ b/2016/tools/xlsxread/src/format_detect_2016.rs
@@ -7,7 +7,7 @@
 ///
 /// 1. `separate-scores`  — header row[0]=="SBD" && row[2]=="TOAN"
 ///    Columns: SBD(0) HOTEN(1) TOAN(2) VAN(3) LY(4) HOA(5) SINH(6) SU(7) DIA(8)
-///              NGOAINGUTN(9) NGOAINGUTL(10) NGOAINGU-total(11)
+///    NGOAINGUTN(9) NGOAINGUTL(10) NGOAINGU-total(11)
 ///    → maps col 11 → tieng_anh; no ngay_sinh / ten_cum_thi / gioi_tinh / DIEM_THI
 ///    → JS: build-database.js:90–116  (processSeparateScoresRow)
 ///
@@ -57,7 +57,7 @@ pub fn is_header_row_2016(row: &[Data]) -> bool {
         return false;
     }
     let first = row[0].to_string().trim().to_uppercase();
-    KNOWN_HEADERS.iter().any(|h| *h == first.as_str())
+    KNOWN_HEADERS.contains(&first.as_str())
 }
 
 // ---------------------------------------------------------------------------
@@ -217,6 +217,9 @@ pub fn process_separate_scores_row(row: &[Data], patterns: &CompiledPatterns) ->
 /// Mirrors `processMappedRow` at build-database.js:119–146.
 /// Gender is normalised: only "Nam" or "Nữ" are kept; everything else → None.
 /// (build-database.js:132: `(rawGioiTinh === "Nam" || rawGioiTinh === "Nữ") ? rawGioiTinh : null`)
+// Mirrors the JS column map one-for-one; grouping the indices into a struct
+// would obscure that correspondence for no benefit.
+#[allow(clippy::too_many_arguments)]
 pub fn process_mapped_row(
     row: &[Data],
     sbd_idx: usize,
@@ -237,8 +240,8 @@ pub fn process_mapped_row(
     // build-database.js:125–126: KNOWN_HEADERS.has(sbdUpper) || KNOWN_HEADERS.has(hoTenUpper)
     let sbd_upper = sbd.to_uppercase();
     let ho_ten_upper = ho_ten.to_uppercase();
-    if KNOWN_HEADERS.iter().any(|h| *h == sbd_upper.as_str())
-        || KNOWN_HEADERS.iter().any(|h| *h == ho_ten_upper.as_str())
+    if KNOWN_HEADERS.contains(&sbd_upper.as_str())
+        || KNOWN_HEADERS.contains(&ho_ten_upper.as_str())
     {
         return None;
     }
diff --git a/2016/tools/xlsxread/src/transform.rs b/2016/tools/xlsxread/src/transform.rs
index 1ea2d68..c228f41 100644
--- a/2016/tools/xlsxread/src/transform.rs
+++ b/2016/tools/xlsxread/src/transform.rs
@@ -326,7 +326,7 @@ mod tests {
         let s = "Toán: 8.5";
         let scores = parse_scores(s, &p);
         assert_eq!(scores.get("toan"), Some(&8.5));
-        assert!(scores.get("ngu_van").is_none());
+        assert!(!scores.contains_key("ngu_van"));
     }
 
     #[test]
diff --git a/2016/tools/xlsxread/tests/golden.rs b/2016/tools/xlsxread/tests/golden.rs
index 47d1309..1e9d647 100644
--- a/2016/tools/xlsxread/tests/golden.rs
+++ b/2016/tools/xlsxread/tests/golden.rs
@@ -125,7 +125,7 @@ fn write_xlsx(path: &Path, sheets: &[(String, Vec<XlsxRow>)]) {
             ws.push_str("    </row>\n");
         }
         ws.push_str("  </sheetData>\n</worksheet>");
-        zip.start_file(&format!("xl/worksheets/sheet{}.xml", i + 1), opts)
+        zip.start_file(format!("xl/worksheets/sheet{}.xml", i + 1), opts)
             .unwrap();
         zip.write_all(ws.as_bytes()).unwrap();
     }
@@ -165,7 +165,7 @@ fn header_row() -> XlsxRow {
 
 fn data_row(idx: usize, scores: &str) -> XlsxRow {
     // Anonymised: name uses sequential pattern, SBD is purely synthetic
-    let name = if idx % 2 == 0 {
+    let name = if idx.is_multiple_of(2) {
         format!("Nguyen Van Test {:03}", idx)
     } else {
         format!("Tran Thi Test {:03}", idx)