diff --git a/components/datetime/src/format/datetime.rs b/components/datetime/src/format/datetime.rs
index 217c1bd5fb0..3e2a37bb946 100644
--- a/components/datetime/src/format/datetime.rs
+++ b/components/datetime/src/format/datetime.rs
@@ -160,6 +160,7 @@ where
             input!(year = input.year);
             input!(related_iso = year.related_iso());
 
+            // Always in latin digits according to spec
             FixedDecimal::from(related_iso)
                 .padded_start(l.to_len() as i16)
                 .write_to(w)?;
diff --git a/components/datetime/src/format/time_zone.rs b/components/datetime/src/format/time_zone.rs
index cfa3e7fe834..650b2ff2782 100644
--- a/components/datetime/src/format/time_zone.rs
+++ b/components/datetime/src/format/time_zone.rs
@@ -579,6 +579,7 @@ impl Iso8601Format {
             return sink.write_char('Z');
         }
 
+        // Always in latin digits according to spec
         FixedDecimal::from(offset.hours_part())
             .padded_start(2)
             .with_sign_display(fixed_decimal::SignDisplay::Always)