diff --git a/packages/utils/src/which.ts b/packages/utils/src/which.ts
index e1facff59..327c60fb4 100644
--- a/packages/utils/src/which.ts
+++ b/packages/utils/src/which.ts
@@ -183,8 +183,8 @@ export interface WhichOptions extends Bun.WhichOptions {
 
 // Darwin-specific "which" shim: consult Xcode/CLT toolchain directories after $PATH.
 // Uses cached directory listings instead of per-command existsSync or xcrun subprocesses.
-function darwinWhich(command: string, _options?: Bun.WhichOptions): string | null {
-	const regular = Bun.which(command);
+function darwinWhich(command: string, options?: Bun.WhichOptions): string | null {
+	const regular = Bun.which(command, options);
 	if (regular) return regular;
 	if (isXcodeBin(command)) {
 		return getMacosToolPaths().get(command) ?? null;
@@ -214,17 +214,19 @@ function cacheKey(command: string, options?: Bun.WhichOptions): CacheKey {
  */
 export function $which(command: string, options?: WhichOptions): string | null {
 	const cachePolicy = options?.cache ?? WhichCachePolicy.Cached;
+	const lookupOptions =
+		options?.PATH !== undefined || process.env.PATH === undefined ? options : { ...options, PATH: process.env.PATH };
 	let key: CacheKey | undefined;
 
 	if (cachePolicy !== WhichCachePolicy.Bypass) {
-		key = cacheKey(command, options);
+		key = cacheKey(command, lookupOptions);
 		if (cachePolicy !== WhichCachePolicy.Fresh) {
 			const cached = toolCache.get(key);
 			if (cached !== undefined) return cached;
 		}
 	}
 
-	const result = whichFresh(command, options);
+	const result = whichFresh(command, lookupOptions);
 	if (key != null && cachePolicy !== WhichCachePolicy.ReadOnly) {
 		toolCache.set(key, result);
 	}
diff --git a/packages/utils/test/which.test.ts b/packages/utils/test/which.test.ts
new file mode 100644
index 000000000..e054975c2
--- /dev/null
+++ b/packages/utils/test/which.test.ts
@@ -0,0 +1,37 @@
+import { afterEach, describe, expect, it } from "bun:test";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import { $which } from "../src/which";
+
+describe("$which", () => {
+	const originalPath = process.env.PATH;
+	const tempDirs: string[] = [];
+
+	afterEach(() => {
+		process.env.PATH = originalPath;
+		for (const dir of tempDirs.splice(0)) {
+			fs.rmSync(dir, { recursive: true, force: true });
+		}
+	});
+
+	it.skipIf(process.platform === "win32")("uses the current process PATH for each cached lookup", () => {
+		const firstDir = fs.mkdtempSync(path.join(os.tmpdir(), "omp-which-first-"));
+		const secondDir = fs.mkdtempSync(path.join(os.tmpdir(), "omp-which-second-"));
+		tempDirs.push(firstDir, secondDir);
+
+		const command = `omp-which-${process.pid}`;
+		const firstExecutable = path.join(firstDir, command);
+		const secondExecutable = path.join(secondDir, command);
+		fs.writeFileSync(firstExecutable, "#!/bin/sh\n");
+		fs.writeFileSync(secondExecutable, "#!/bin/sh\n");
+		fs.chmodSync(firstExecutable, 0o755);
+		fs.chmodSync(secondExecutable, 0o755);
+
+		process.env.PATH = firstDir;
+		expect($which(command)).toBe(firstExecutable);
+
+		process.env.PATH = secondDir;
+		expect($which(command)).toBe(secondExecutable);
+	});
+});