diff --git a/crates/sylpheed-formats/src/slb.rs b/crates/sylpheed-formats/src/slb.rs
index d7f75e65..78a979f2 100644
--- a/crates/sylpheed-formats/src/slb.rs
+++ b/crates/sylpheed-formats/src/slb.rs
@@ -264,7 +264,10 @@ pub fn to_xma_riffs(slb: &[u8]) -> Vec<Vec<u8>> {
     }
     let mut pos = 0usize;
     while let Some(ri) = find(slb, b"RIFF", pos) {
-        // Parse this sub-wave's fmt + data (declared size is honest per sub-wave).
+        // Parse this sub-wave's fmt + data. The declared `data` size is an
+        // UPPER bound, not an exact one: 5 296 of 7 586 banks declare more than
+        // the entry holds and none declares exactly what it holds, so the clamp
+        // below is load-bearing (docs/re/structures/slb-data-offset.md).
         let Some(fi) = find(slb, b"fmt ", ri) else { break };
         let Some(fsz) = le32(slb, fi + 4) else { break };
         let Some(fmt_end) = fi.checked_add(8).and_then(|v| v.checked_add(fsz as usize)) else {
@@ -298,10 +301,12 @@ pub fn to_xma_riff(slb: &[u8]) -> Option<Vec<u8>> {
     if let Some(ri) = find(slb, b"RIFF", 0) {
         // RIFF layout: a `.slb` is an XACT bank of one or more sub-waves, each
         // `[seek][RIFF: fmt + Dmmy pad + data][declared_size XMA bytes]`. Take the
-        // FIRST sub-wave, bounded by its **declared `data` size** (which is
-        // honest per sub-wave). Decoding to end-of-file instead would append the
-        // later sub-waves — for multi-take story movies those are ALTERNATE takes,
-        // which is what made S10–S16 play the wrong audio.
+        // FIRST sub-wave, bounded by its **declared `data` size** — which is an
+        // upper bound only (69.8 % of banks over-declare it, so the clamp
+        // matters), but still the right boundary to cut at. Decoding to
+        // end-of-file instead would append the later sub-waves — for multi-take
+        // story movies those are ALTERNATE takes, which is what made S10–S16
+        // play the wrong audio.
         let fi = find(slb, b"fmt ", ri)?;
         let fsz = le32(slb, fi + 4)? as usize;
         let fmt_end = fi.checked_add(8)?.checked_add(fsz)?;