diff --git a/src/interactions/pointer.js b/src/interactions/pointer.js
index c92addcff7..f0c0f765b0 100644
--- a/src/interactions/pointer.js
+++ b/src/interactions/pointer.js
@@ -1,5 +1,6 @@
 import {pointer as pointof} from "d3";
 import {composeRender} from "../mark.js";
+import {isArray} from "../options.js";
 import {applyFrameAnchor} from "../style.js";
 
 const states = new WeakMap();
@@ -126,7 +127,11 @@ function pointerK(kx, ky, {x, y, px, py, maxRadius = 40, channels, render, ...op
 
         // Dispatch the value. When simultaneously exiting this facet and
         // entering a new one, prioritize the entering facet.
-        if (!(i == null && facetState?.size > 1)) context.dispatchValue(i == null ? null : data[i]);
+        if (!(i == null && facetState?.size > 1)) {
+          const value = i == null ? null : isArray(data) ? data[i] : data.get(i);
+          context.dispatchValue(value);
+        }
+
         return r;
       }
 
diff --git a/src/options.js b/src/options.js
index 934a5966cf..ac9caca472 100644
--- a/src/options.js
+++ b/src/options.js
@@ -7,7 +7,7 @@ import {timeInterval, utcInterval} from "./time.js";
 export const TypedArray = Object.getPrototypeOf(Uint8Array);
 const objectToString = Object.prototype.toString;
 
-function isArray(value) {
+export function isArray(value) {
   return value instanceof Array || value instanceof TypedArray;
 }
 
@@ -608,7 +608,7 @@ export function maybeClip(clip) {
 }
 
 // https://github.com/observablehq/stdlib/blob/746ca2e69135df6178e4f3a17244def35d8d6b20/src/arrow.js#L4C1-L17C1
-export function isArrowTable(value) {
+function isArrowTable(value) {
   return (
     value &&
     typeof value.getChild === "function" &&
diff --git a/src/transforms/basic.js b/src/transforms/basic.js
index cd846d8ef1..8146ae9381 100644
--- a/src/transforms/basic.js
+++ b/src/transforms/basic.js
@@ -1,6 +1,7 @@
 import {randomLcg} from "d3";
 import {ascendingDefined, descendingDefined} from "../defined.js";
-import {dataify, isDomainSort, isOptions, maybeValue, valueof} from "../options.js";
+import {isArray, isDomainSort, isOptions} from "../options.js";
+import {dataify, maybeValue, valueof} from "../options.js";
 
 export function basic({filter: f1, sort: s1, reverse: r1, transform: t1, initializer: i1, ...options} = {}, transform) {
   // If both t1 and t2 are defined, returns a composite transform that first
@@ -101,7 +102,9 @@ function sortTransform(value) {
 
 function sortData(compare) {
   return (data, facets) => {
-    const compareData = (i, j) => compare(data[i], data[j]);
+    const compareData = isArray(data)
+      ? (i, j) => compare(data[i], data[j])
+      : (i, j) => compare(data.get(i), data.get(j));
     return {data, facets: facets.map((I) => I.slice().sort(compareData))};
   };
 }
diff --git a/src/transforms/group.js b/src/transforms/group.js
index 0f9ad95a57..b3320efd65 100644
--- a/src/transforms/group.js
+++ b/src/transforms/group.js
@@ -1,38 +1,9 @@
-import {
-  InternSet,
-  deviation,
-  group as grouper,
-  max,
-  maxIndex,
-  mean,
-  median,
-  min,
-  minIndex,
-  mode,
-  rollup,
-  sort,
-  sum,
-  variance
-} from "d3";
+import {InternSet, group as grouper, rollup, sort} from "d3";
+import {deviation, max, maxIndex, mean, median, min, minIndex, mode, sum, variance} from "d3";
 import {ascendingDefined} from "../defined.js";
-import {
-  arrayify,
-  column,
-  identity,
-  isObject,
-  isTemporal,
-  labelof,
-  maybeApplyInterval,
-  maybeColorChannel,
-  maybeColumn,
-  maybeInput,
-  maybeTuple,
-  percentile,
-  range,
-  second,
-  take,
-  valueof
-} from "../options.js";
+import {maybeApplyInterval, maybeColorChannel, maybeColumn, maybeInput, maybeTuple} from "../options.js";
+import {isArray, isObject, isTemporal} from "../options.js";
+import {column, identity, labelof, percentile, range, second, take, valueof} from "../options.js";
 import {basic} from "./basic.js";
 
 // Group on {z, fill, stroke}.
@@ -445,8 +416,7 @@ export function find(test) {
   if (typeof test !== "function") throw new Error(`invalid test function: ${test}`);
   return {
     reduceIndex(I, V, {data}) {
-      data = arrayify(data);
-      return V[I.find((i) => test(data[i], i, data))];
+      return V[I.find(isArray(data) ? (i) => test(data[i], i, data) : (i) => test(data.get(i), i, data))];
     }
   };
 }
diff --git a/src/transforms/stack.js b/src/transforms/stack.js
index 5a03bbf84e..20d7342e03 100644
--- a/src/transforms/stack.js
+++ b/src/transforms/stack.js
@@ -2,7 +2,7 @@ import {InternMap, cumsum, greatest, group, groupSort, max, min, rollup, sum} fr
 import {ascendingDefined, descendingDefined} from "../defined.js";
 import {withTip} from "../mark.js";
 import {maybeApplyInterval, maybeColumn, maybeZ, maybeZero} from "../options.js";
-import {arrayify, column, field, lengthof, mid, one, range, valueof} from "../options.js";
+import {column, field, isArray, lengthof, mid, one, range, valueof} from "../options.js";
 import {basic} from "./basic.js";
 import {exclusiveFacets} from "./exclusiveFacets.js";
 
@@ -252,7 +252,7 @@ function maybeOrder(order, offset, ky) {
     return orderAccessor(field(order));
   }
   if (typeof order === "function") return (order.length === 1 ? orderAccessor : orderComparator)(order);
-  if (Array.isArray(order)) return orderGiven(order);
+  if (isArray(order)) return orderGiven(order);
   throw new Error(`invalid order: ${order}`);
 }
 
@@ -328,8 +328,7 @@ function orderAccessor(f) {
 
 function orderComparator(f) {
   return (data) => {
-    data = arrayify(data);
-    return (i, j) => f(data[i], data[j]);
+    return isArray(data) ? (i, j) => f(data[i], data[j]) : (i, j) => f(data.get(i), data.get(j));
   };
 }