diff --git a/packages/compiler/src/frontend/lowering/containers/array-pipelines.ts b/packages/compiler/src/frontend/lowering/containers/array-pipelines.ts
index 7c2e07b1c..197af2a9e 100644
--- a/packages/compiler/src/frontend/lowering/containers/array-pipelines.ts
+++ b/packages/compiler/src/frontend/lowering/containers/array-pipelines.ts
@@ -950,11 +950,14 @@ class PipelineFusion {
    * nothing assigns after their declaration: `fn`'s own locals and
    * parameters, written neither by `fn` nor by any closure that shares
    * them, and not by the callback body. A binding a local class captures
-   * counts as written, since its methods may assign it. The callback must
+   * counts as written, since its methods may assign it; so does a binding
+   * a method reads through its class's captures. The callback must
    * not observe the ambient receiver (AmbientReceiverReaders). */
   private stableTarget(fn: IrFunction): InlineTarget {
     const locals = new Map(fn.locals.map((l) => [l.id, l]));
-    const inherited = new Set((fn.captures ?? []).map((c) => c.localId));
+    const inherited = new Set(
+      [...(fn.captures ?? []), ...(fn.classCaptures ?? [])].map((c) => c.localId),
+    );
     const written = this.written.get(fn.name);
     const classCaptured = this.classCaptured(fn);
     return (arg) => {
diff --git a/packages/compiler/test/array-pipeline-fusion.test.ts b/packages/compiler/test/array-pipeline-fusion.test.ts
index e41e378a3..2c0c138ce 100644
--- a/packages/compiler/test/array-pipeline-fusion.test.ts
+++ b/packages/compiler/test/array-pipeline-fusion.test.ts
@@ -249,3 +249,20 @@ console.log(out.join(","), hit);
 ${postlude}`);
   expect(helperCalls(init(mod))).toEqual(["%arr.loop", "%arr.loop"]);
 });
+
+test("a lone call in a local class's method keeps its helper for the class's captures", async () => {
+  const mod = await lowerSource(`${prelude}
+let k = 1;
+class Box {
+  set(v: number): void { k = v; }
+  go(): number[] {
+    const b = new Box();
+    return rows.map((r) => { b.set(r.id); return r.value + k; });
+  }
+}
+console.log(new Box().go().join(","));
+${postlude}`);
+  const go = mod.functions.find((f) => f.name.endsWith(".Box.go"));
+  expect(go).toBeDefined();
+  expect(helperCalls(go!)).toEqual(["%arr.map"]);
+});