diff --git a/crates/edit/src/captions.rs b/crates/edit/src/captions.rs
--- a/crates/edit/src/captions.rs
+++ b/crates/edit/src/captions.rs
@@ -156,8 +156,9 @@ pub fn trim_caption(seq: &mut Sequence, id: ClipId, edge: Edge, delta: Tick, ctx
     let (prev, next) = neighbours(tr, id);
     let c = tr.caption_mut(id).ok_or(EditError::NoItem(id))?;
     let d = match edge {
-        Edge::In => delta.clamp(prev - c.start, c.duration - ctx.min_duration),
-        Edge::Out => delta.clamp(ctx.min_duration - c.duration, next - c.end()),
+        // bounds never cross: a caption already shorter than the minimum cannot shrink
+        Edge::In => delta.clamp((prev - c.start).min(Tick::ZERO), (c.duration - ctx.min_duration).max(Tick::ZERO)),
+        Edge::Out => delta.clamp((ctx.min_duration - c.duration).min(Tick::ZERO), (next - c.end()).max(Tick::ZERO)),
     };
     if d == Tick::ZERO {
         return Err(EditError::Nothing);
diff --git a/crates/edit/src/tests.rs b/crates/edit/src/tests.rs
--- a/crates/edit/src/tests.rs
+++ b/crates/edit/src/tests.rs
@@ -1079,3 +1079,30 @@ fn moving_an_edge_keeps_the_media_under_the_timeline() {
         }
     }
 }
+
+#[test]
+fn trim_caption_shorter_than_min_duration_does_not_cross_bounds() {
+    use filmcraft_project::{Caption, CaptionFormat, CaptionTrack};
+    for edge in [Edge::In, Edge::Out] {
+        let mut fx = Fx::new();
+        let tid = TrackId(900);
+        let mut tr = CaptionTrack::new(tid, "c".into(), CaptionFormat::Subtitle);
+        for (id, start) in [(1, 0), (2, 1000)] {
+            tr.captions.push(Caption {
+                id: ClipId(id),
+                start: Tick(start),
+                duration: Tick(1000),
+                text: "x".into(),
+                speaker: None,
+                cue_id: None,
+                settings: String::new(),
+            });
+        }
+        fx.seq.caption_tracks.push(tr);
+        let ctx = Fx::ctx(&mut fx.next);
+        let _ = crate::captions::trim_caption(&mut fx.seq, ClipId(2), edge, Tick(5), &ctx);
+        let c = fx.seq.find_caption(ClipId(2)).unwrap().1;
+        assert!(c.start >= Tick(1000), "{edge:?}: start moved back into previous caption: {:?}", c.start);
+        assert!(c.duration >= Tick(1000), "{edge:?}: caption shrank: {:?}", c.duration);
+    }
+}