3 files changed, 5 insertions, 4 deletions
diff --git a/crates/typst-layout/src/math/mat.rs b/crates/typst-layout/src/math/mat.rs
index 6c8b0455..24104f4e 100644
--- a/crates/typst-layout/src/math/mat.rs
+++ b/crates/typst-layout/src/math/mat.rs
@@ -127,7 +127,9 @@ fn layout_vec_body(
     let denom_style = style_for_denominator(styles);
     let mut flat = vec![];
     for child in column {
-        flat.push(ctx.layout_into_run(child, styles.chain(&denom_style))?);
+        // We allow linebreaks in cases and vectors, which are functionally
+        // identical to commas.
+        flat.extend(ctx.layout_into_run(child, styles.chain(&denom_style))?.rows());
     }
     // We pad ascent and descent with the ascent and descent of the paren
     // to ensure that normal vectors are aligned with others unless they are
diff --git a/crates/typst-layout/src/math/shared.rs b/crates/typst-layout/src/math/shared.rs
index 13477c10..74e62e8f 100644
--- a/crates/typst-layout/src/math/shared.rs
+++ b/crates/typst-layout/src/math/shared.rs
@@ -121,7 +121,6 @@ pub fn stack(
     alternator: LeftRightAlternator,
     minimum_ascent_descent: Option<(Abs, Abs)>,
 ) -> Frame {
-    let rows: Vec<_> = rows.into_iter().flat_map(|r| r.rows()).collect();
     let AlignmentResult { points, width } = alignments(&rows);
     let rows: Vec<_> = rows
         .into_iter()
diff --git a/crates/typst-layout/src/math/underover.rs b/crates/typst-layout/src/math/underover.rs
index b1d4825b..1a2c8db6 100644
--- a/crates/typst-layout/src/math/underover.rs
+++ b/crates/typst-layout/src/math/underover.rs
@@ -297,7 +297,7 @@ fn layout_underoverspreader(
             if let Some(annotation) = annotation {
                 let under_style = style_for_subscript(styles);
                 let annotation_styles = styles.chain(&under_style);
-                rows.push(ctx.layout_into_run(annotation, annotation_styles)?);
+                rows.extend(ctx.layout_into_run(annotation, annotation_styles)?.rows());
             }
             0
         }
@@ -305,7 +305,7 @@ fn layout_underoverspreader(
             if let Some(annotation) = annotation {
                 let over_style = style_for_superscript(styles);
                 let annotation_styles = styles.chain(&over_style);
-                rows.push(ctx.layout_into_run(annotation, annotation_styles)?);
+                rows.extend(ctx.layout_into_run(annotation, annotation_styles)?.rows());
             }
             rows.push(stretched.into());
             rows.push(MathRun::new(vec![body]));