diff --git a/tests/acceptance/setup/registrationRuntimeEnvironmentCli.test.ts b/tests/acceptance/setup/registrationRuntimeEnvironmentCli.test.ts
index 9617e19b8b..7af5a60a7e 100644
--- a/tests/acceptance/setup/registrationRuntimeEnvironmentCli.test.ts
+++ b/tests/acceptance/setup/registrationRuntimeEnvironmentCli.test.ts
@@ -318,7 +318,13 @@ cliTest(
         mcp: {
           rea: clientRegistrationEntry(
             "opencode",
-            [resolve("scripts/rea.mjs"), "mcp"],
+            // Windows launches JavaScript through Node; otherwise setup repairs
+            // the command before this test can exercise layered environment data.
+            [
+              ...(process.platform === "win32" ? [process.execPath] : []),
+              resolve("scripts/rea.mjs"),
+              "mcp",
+            ],
             env,
           ),
         },