diff --git a/test/es6.test.js b/test/es6.test.js
index b49c204..a0ceaeb 100644
--- a/test/es6.test.js
+++ b/test/es6.test.js
@@ -6,24 +6,24 @@ import check from './utils.js';
 const testSuite = suite('module-types');
 
 testSuite('detects es6 imports', () => {
-  assert.ok(check('import {foo, bar} from "mylib";', isES6Import, true));
-  assert.ok(check('import * as foo from "mod.js";', isES6Import, true));
-  assert.ok(check('import "mylib2";', isES6Import, true));
-  assert.ok(check('import foo from "mod.js";', isES6Import, true));
-  assert.ok(check('import("foo");', isES6Import, true));
+  assert.ok(check('import {foo, bar} from "mylib";', isES6Import));
+  assert.ok(check('import * as foo from "mod.js";', isES6Import));
+  assert.ok(check('import "mylib2";', isES6Import));
+  assert.ok(check('import foo from "mod.js";', isES6Import));
+  assert.ok(check('import("foo");', isES6Import));
 });
 
 testSuite('detects es6 exports', () => {
-  assert.ok(check('export default 123;', isES6Export, true));
-  assert.ok(check('export {foo, bar}; function foo() {} function bar() {}', isES6Export, true));
-  assert.ok(check('export { D as default }; class D {}', isES6Export, true));
-  assert.ok(check('export function inc() { counter++; }', isES6Export, true));
-  assert.ok(check('export * from "mod";', isES6Export, true));
+  assert.ok(check('export default 123;', isES6Export));
+  assert.ok(check('export {foo, bar}; function foo() {} function bar() {}', isES6Export));
+  assert.ok(check('export { D as default }; class D {}', isES6Export));
+  assert.ok(check('export function inc() { counter++; }', isES6Export));
+  assert.ok(check('export * from "mod";', isES6Export));
 });
 
 testSuite('detects dynamic imports', () => {
-  assert.ok(check('import("./bar");', isDynamicImport, true));
-  assert.ok(check('function foo() { import("./bar"); }', isDynamicImport, true));
+  assert.ok(check('import("./bar");', isDynamicImport));
+  assert.ok(check('function foo() { import("./bar"); }', isDynamicImport));
 });
 
 testSuite.run();
diff --git a/test/is-require.test.js b/test/is-require.test.js
index 9cf4bc5..0b69d0e 100644
--- a/test/is-require.test.js
+++ b/test/is-require.test.js
@@ -21,7 +21,7 @@ testSuite('detects top-level (i.e., top of file) require function calls', () =>
 
 testSuite('does not fail on es6', () => {
   assert.not.throws(() => {
-    check('import require from "mylib"; \nrequire();', isTopLevelRequire, true);
+    check('import require from "mylib"; \nrequire();', isTopLevelRequire);
   });
 });
 
diff --git a/test/utils.js b/test/utils.js
index a99f346..8beb6cc 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -2,8 +2,8 @@ import Walker from 'node-source-walk';
 
 // Checks whether or not the checker succeeds on
 // a node in the AST of the given source code
-function check(code, checker, harmony) {
-  const walker = new Walker({ esprimaHarmony: Boolean(harmony) });
+function check(code, checker) {
+  const walker = new Walker();
   let found = false;
 
   walker.walk(code, node => {