diff --git a/library/src/layout/container.rs b/library/src/layout/container.rs
index 166d6c09c..ef5fbe5dd 100644
--- a/library/src/layout/container.rs
+++ b/library/src/layout/container.rs
@@ -132,6 +132,9 @@ impl Layout for BoxElem {
         let pod = Regions::one(size, expand);
         let mut frame = body.layout(vt, styles, pod)?.into_frame();
 
+        // Enforce correct size.
+        *frame.size_mut() = expand.select(size, frame.size());
+
         // Apply baseline shift.
         let shift = self.baseline(styles).relative_to(frame.height());
         if !shift.is_zero() {
@@ -377,10 +380,17 @@ impl Layout for BlockElem {
                 pod.last = None;
             }
 
-            body.layout(vt, styles, pod)?.into_frames()
+            let mut frames = body.layout(vt, styles, pod)?.into_frames();
+            for (frame, &height) in frames.iter_mut().zip(&heights) {
+                *frame.size_mut() =
+                    expand.select(Size::new(size.x, height), frame.size());
+            }
+            frames
         } else {
             let pod = Regions::one(size, expand);
-            body.layout(vt, styles, pod)?.into_frames()
+            let mut frames = body.layout(vt, styles, pod)?.into_frames();
+            *frames[0].size_mut() = expand.select(size, frames[0].size());
+            frames
         };
 
         // Clip the contents
diff --git a/library/src/layout/flow.rs b/library/src/layout/flow.rs
index cd7b1f606..b45c39c22 100644
--- a/library/src/layout/flow.rs
+++ b/library/src/layout/flow.rs
@@ -1,6 +1,8 @@
 use super::{AlignElem, BlockElem, ColbreakElem, ParElem, PlaceElem, Spacing, VElem};
 use crate::prelude::*;
-use crate::visualize::{CircleElem, EllipseElem, ImageElem, RectElem, SquareElem};
+use crate::visualize::{
+    CircleElem, EllipseElem, ImageElem, PathElem, PolygonElem, RectElem, SquareElem,
+};
 
 /// Arrange spacing, paragraphs and block-level elements into a flow.
 ///
@@ -42,6 +44,8 @@ impl Layout for FlowElem {
                 || child.is::<EllipseElem>()
                 || child.is::<CircleElem>()
                 || child.is::<ImageElem>()
+                || child.is::<PolygonElem>()
+                || child.is::<PathElem>()
             {
                 let layoutable = child.with::<dyn Layout>().unwrap();
                 layouter.layout_single(vt, layoutable, styles)?;
diff --git a/library/src/layout/mod.rs b/library/src/layout/mod.rs
index d12ce158e..0fed1a34e 100644
--- a/library/src/layout/mod.rs
+++ b/library/src/layout/mod.rs
@@ -57,6 +57,8 @@ use crate::meta::DocumentElem;
 use crate::prelude::*;
 use crate::shared::BehavedBuilder;
 use crate::text::{LinebreakElem, SmartQuoteElem, SpaceElem, TextElem};
+use crate::visualize::PathElem;
+use crate::visualize::PolygonElem;
 use crate::visualize::{CircleElem, EllipseElem, ImageElem, RectElem, SquareElem};
 
 /// Root-level layout.
@@ -192,6 +194,8 @@ fn realize_block<'a>(
         && !content.is::<EllipseElem>()
         && !content.is::<CircleElem>()
         && !content.is::<ImageElem>()
+        && !content.is::<PolygonElem>()
+        && !content.is::<PathElem>()
         && !applicable(content, styles)
     {
         return Ok((content.clone(), styles));
diff --git a/library/src/visualize/shape.rs b/library/src/visualize/shape.rs
index ba7f052ff..c899ad6d9 100644
--- a/library/src/visualize/shape.rs
+++ b/library/src/visualize/shape.rs
@@ -483,7 +483,7 @@ fn layout(
 
     let mut frame;
     if let Some(child) = body {
-        let region = resolved.unwrap_or(regions.base());
+        let mut region = resolved.unwrap_or(regions.base());
         if kind.is_round() {
             inset = inset.map(|side| side + Ratio::new(0.5 - SQRT_2 / 4.0));
         }
@@ -498,10 +498,13 @@ fn layout(
         // the result is really a square or circle.
         if kind.is_quadratic() {
             let length = frame.size().max_by_side().min(region.min_by_side());
-            let size = Size::splat(length);
-            let pod = Regions::one(size, Axes::splat(true));
+            region = Size::splat(length);
+            let pod = Regions::one(region, Axes::splat(true));
             frame = child.layout(vt, styles, pod)?.into_frame();
         }
+
+        // Enforce correct size.
+        *frame.size_mut() = expand.select(region, frame.size());
     } else {
         // The default size that a shape takes on if it has no child and
         // enough space.
diff --git a/tests/ref/compiler/construct.png b/tests/ref/compiler/construct.png
index eba9aa9fd..3dac041fd 100644
Binary files a/tests/ref/compiler/construct.png and b/tests/ref/compiler/construct.png differ
diff --git a/tests/ref/layout/container.png b/tests/ref/layout/container.png
index ce298d29a..eff06f1a7 100644
Binary files a/tests/ref/layout/container.png and b/tests/ref/layout/container.png differ
diff --git a/tests/typ/layout/container.typ b/tests/typ/layout/container.typ
index 0b30c4e1b..d9b62f5e8 100644
--- a/tests/typ/layout/container.typ
+++ b/tests/typ/layout/container.typ
@@ -9,6 +9,16 @@ Spaced \
 #box(height: 0.5cm) \
 Apart
 
+---
+// Test box sizing.
+#box(width: 50pt, height: 50pt, fill: yellow, path(
+  fill: purple,
+  (0pt, 0pt),
+  (30pt, 30pt),
+  (0pt, 30pt),
+  (30pt, 0pt),
+))
+
 ---
 // Test fr box.
 Hello #box(width: 1fr, rect(height: 0.7em, width: 100%)) World