diff --git a/tests/support/support.ts b/tests/support/support.ts
index d8a1b337a..2064438fa 100644
--- a/tests/support/support.ts
+++ b/tests/support/support.ts
@@ -29,13 +29,17 @@ export const heartwoodShortSha = (
   await Fs.readFile(`${supportDir}/heartwood-version`, "utf8")
 ).substring(0, 7);
 
-process.env.PATH = [
-  Path.join(tmpDir, "bin", heartwoodShortSha),
-  process.env.PATH,
-].join(Path.delimiter);
+const binaryPath = Path.join(tmpDir, "bin", heartwoodShortSha);
+process.env.PATH = [binaryPath, process.env.PATH].join(Path.delimiter);
 
 // Assert that the `rad` CLI is installed and has the correct version.
 export async function assertRadInstalled(): Promise<void> {
+  const { stdout: which } = await execa("which", ["rad"]);
+  if (Path.dirname(which) !== binaryPath) {
+    throw new Error(
+      `rad path doesn't match used rad binary: ${binaryPath} !== ${which}`,
+    );
+  }
   const { stdout: version } = await execa("rad", ["--version"]);
   if (!version.includes(heartwoodShortSha)) {
     throw new Error(