@@ -24,6 +24,24 @@ for (const [id, flag] of experimentalBuiltins) {
   ], { status: 0 });
 }
 
+const schemelessExperimentalBuiltins = [
+  ['stream/iter', '--experimental-stream-iter'],
+  ['zlib/iter', '--experimental-stream-iter'],
+];
+
+for (const [id, flag] of schemelessExperimentalBuiltins) {
+  const nodeBuiltin = `node:${id}`;
+
+  spawnSyncAndAssert(process.execPath, [
+    '-e', `const assert = require('node:assert'); const { builtinModules } = require('node:module'); assert(!builtinModules.includes('${id}')); assert(!builtinModules.includes('${nodeBuiltin}')); assert.throws(() => require('${id}'), { code: 'MODULE_NOT_FOUND' }); assert.throws(() => require('${nodeBuiltin}'), { code: 'ERR_UNKNOWN_BUILTIN_MODULE' });`,
+  ], { status: 0 });
+
+  spawnSyncAndAssert(process.execPath, [
+    flag,
+    '-e', `const assert = require('node:assert'); const { builtinModules } = require('node:module'); assert(builtinModules.includes('${id}')); assert(!builtinModules.includes('${nodeBuiltin}')); require('${id}'); require('${nodeBuiltin}');`,
+  ], { status: 0 });
+}
+
 // node:ffi is enabled by default in builds with FFI support and can be
 // disabled with --no-experimental-ffi.
 if (common.hasFFI) {