diff --git a/src/package-transpilation-registry.js b/src/package-transpilation-registry.js
index b8a792339..7943e80e8 100644
--- a/src/package-transpilation-registry.js
+++ b/src/package-transpilation-registry.js
@@ -23,7 +23,7 @@ class PackageTranspilationRegistry {
       name: packageName,
       meta: packageMeta,
       path: packagePath,
-      specs: config
+      specs: config.map(spec => Object.assign({}, spec))
     }
   }