diff --git a/cetz-core/src/lib.rs b/cetz-core/src/lib.rs
index 7c4f26c5..5e1535ce 100644
--- a/cetz-core/src/lib.rs
+++ b/cetz-core/src/lib.rs
@@ -1,6 +1,7 @@
 use ciborium::de::from_reader;
 use ciborium::ser::into_writer;
 use serde::Deserialize;
+use serde::Serialize;
 use wasm_minimal_protocol::*;
 
 initiate_protocol!();
@@ -103,3 +104,53 @@ pub fn cubic_extrema_func(input: &[u8]) -> Vec<u8> {
         }
     }
 }
+
+#[derive(Serialize, Deserialize)]
+struct Bounds {
+    low: Point,
+    high: Point,
+}
+
+/// Compute the axis-aligned bounding box (aabb).
+fn aabb(init: Option<Bounds>, pts: Vec<Point>) -> Result<Bounds, String> {
+    let mut bounds = match init {
+        Some(init) => init,
+        None => Bounds {
+            low: pts.first().unwrap().clone(),
+            high: pts.first().unwrap().clone(),
+        },
+    };
+    for pt in pts {
+        if pt.len() != 3 {
+            return Err("Point must have 3 dimensions".to_string());
+        }
+        for dim in 0..pt.len() {
+            if pt[dim] < bounds.low[dim] {
+                bounds.low[dim] = pt[dim];
+            }
+            if bounds.high[dim] < pt[dim] {
+                bounds.high[dim] = pt[dim];
+            }
+        }
+    }
+    Ok(bounds)
+}
+
+#[derive(Deserialize)]
+struct AabbArgs {
+    pts: Vec<Point>,
+    init: Option<Bounds>,
+}
+
+#[wasm_func]
+pub fn aabb_func(input: &[u8]) -> Result<Vec<u8>, String> {
+    match from_reader::<AabbArgs, _>(input) {
+        Ok(input) => {
+            let mut buf = Vec::new();
+            let bounds = aabb(input.init, input.pts)?;
+            into_writer(&bounds, &mut buf).unwrap();
+            Ok(buf)
+        }
+        Err(e) => Err(e.to_string()),
+    }
+}
diff --git a/src/aabb.typ b/src/aabb.typ
index 42a972f9..4b2b8edb 100644
--- a/src/aabb.typ
+++ b/src/aabb.typ
@@ -1,4 +1,5 @@
 #import "vector.typ"
+#let cetz-core = plugin("../cetz-core/cetz_core.wasm")
 
 /// Compute an axis aligned bounding box (aabb) for a list of <Type>vectors</Type>.
 ///
@@ -6,33 +7,10 @@
 /// - init (aabb): Initial aabb
 /// -> aabb
 #let aabb(pts, init: none) = {
-  if type(pts) == array {
-    let bounds = if init == none and 0 < pts.len() {
-      let pt = pts.at(0)
-      (low: pt, high: pt)
-    } else {
-      init
-    }
-    for pt in pts {
-      assert(type(pt) == array and pt.len() == 3, message: repr(init) + repr(pts))
-      let (x, y, z) = pt
-
-      let (lo-x, lo-y, lo-z) = bounds.low
-      bounds.low = (calc.min(lo-x, x), calc.min(lo-y, y), calc.min(lo-z, z))
-
-      let (hi-x, hi-y, hi-z) = bounds.high
-      bounds.high = (calc.max(hi-x, x), calc.max(hi-y, y), calc.max(hi-z, z))
-    }
-    return bounds
-  } else if type(pts) == dictionary {
-    if init == none {
-      return pts
-    } else {
-      return aabb((pts.low, pts.high,), init: init)
-    }
-  }
-
-  panic("Expected array of vectors or bbox dictionary, got: " + repr(pts))
+  let args = (pts: pts, init: init)
+  let encoded = cbor.encode(args)
+  let bounds = cbor(cetz-core.aabb_func(encoded))
+  return bounds
 }
 
 /// Get the mid-point of an AABB as vector.
diff --git a/src/process.typ b/src/process.typ
index 47ffb416..f27b4da9 100644
--- a/src/process.typ
+++ b/src/process.typ
@@ -26,7 +26,7 @@
             path-util.bounds(drawable.segments)
           } else if drawable.type == "content" {
             let (x, y, _, w, h,) = drawable.pos + (drawable.width, drawable.height)
-            ((x + w / 2, y - h / 2, 0), (x - w / 2, y + h / 2, 0))
+            ((x + w / 2, y - h / 2, 0.0), (x - w / 2, y + h / 2, 0.0))
           },
           init: bounds
         )
@@ -81,7 +81,8 @@
     let r = element(ctx, el)
     if r != none {
       if r.bounds != none {
-        bounds = aabb.aabb(r.bounds, init: bounds)
+        let pts = (r.bounds.low, r.bounds.high,)
+        bounds = aabb.aabb(pts, init: bounds)
       }
       ctx = r.ctx
       drawables += r.drawables