diff --git a/packages/compartment-mapper/src/node-modules.js b/packages/compartment-mapper/src/node-modules.js
index 1c5cff649b..056070f12a 100644
--- a/packages/compartment-mapper/src/node-modules.js
+++ b/packages/compartment-mapper/src/node-modules.js
@@ -566,7 +566,7 @@ const graphPackages = async (
  * @param {Graph} graph
  * @param {Set<string>} tags - build tags about the target environment
  * for selecting relevant exports, e.g., "browser" or "node".
- * @param {object} policy
+ * @param {object|undefined} policy
  * @returns {CompartmentMapDescriptor}
  */
 const translateGraph = (
diff --git a/packages/compartment-mapper/src/policy-format.js b/packages/compartment-mapper/src/policy-format.js
index 8484b4b6f8..a439f89045 100644
--- a/packages/compartment-mapper/src/policy-format.js
+++ b/packages/compartment-mapper/src/policy-format.js
@@ -122,7 +122,7 @@ export const assertPackagePolicy = (allegedPackagePolicy, path, url) => {
   const packagePolicy = Object(allegedPackagePolicy);
   assert(
     allegedPackagePolicy === packagePolicy && !isArray(allegedPackagePolicy),
-    `${path} must be an object, got ${allegedPackagePolicy}${inUrl}`,
+    `${path} must be an object, got ${q(allegedPackagePolicy)}${inUrl}`,
   );
   const {
     packages,
diff --git a/packages/compartment-mapper/src/policy.js b/packages/compartment-mapper/src/policy.js
index ac2502b97c..79d7ef1eb2 100644
--- a/packages/compartment-mapper/src/policy.js
+++ b/packages/compartment-mapper/src/policy.js
@@ -17,7 +17,7 @@ import {
   isAllowingEverything,
 } from './policy-format.js';
 
-const { entries, values, assign, keys, freeze } = Object;
+const { create, entries, values, assign, keys, freeze } = Object;
 const q = JSON.stringify;
 
 /**
@@ -138,7 +138,7 @@ export const getPolicyForPackage = (namingKit, policy) => {
     return policy.resources[canonicalName];
   } else {
     // Allow skipping policy entries for packages with no powers.
-    return {};
+    return create(null);
   }
 };