diff --git a/test/compat.spec.ts b/test/compat.spec.ts
new file mode 100644
index 00000000..0b24f14b
--- /dev/null
+++ b/test/compat.spec.ts
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2021 StApps
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {lightweightProjectFromPath} from '@openstapps/core-tools/lib/easy-ast/easy-ast';
+import {LightweightProject} from '@openstapps/core-tools/lib/easy-ast/types/lightweight-project';
+import {expect} from 'chai';
+import {reduce} from 'lodash';
+
+process.on('unhandledRejection', (err) => {
+  throw err;
+});
+
+describe('Mapping Compatibility', () => {
+  let project: LightweightProject;
+
+  before(function () {
+    this.timeout(15000);
+    this.slow(10000);
+
+    project = lightweightProjectFromPath('src');
+  });
+
+  it('non-exported definitions should not have duplicate names across files', () => {
+    reduce(project, (result, file) => reduce(file, (result2, _, key) => {
+      expect(result2[key]).to.be.undefined;
+      return {
+        [key]: true,
+        ...result2,
+      };
+    }, result), {} as Record<string, boolean>);
+  });
+});