diff --git a/packages/builders/scripts/vats/priceFeedSupport.js b/packages/builders/scripts/vats/priceFeedSupport.js
index 309d4f0a821..5f916d3c793 100644
--- a/packages/builders/scripts/vats/priceFeedSupport.js
+++ b/packages/builders/scripts/vats/priceFeedSupport.js
@@ -2,41 +2,33 @@
 
 import { DEFAULT_CONTRACT_TERMS } from '../inter-protocol/price-feed-core.js';
 
-const ORACLE_ADDRESSES = [
-  // XXX These are the oracle addresses. They must be provided before the chain
-  // is running, which means they must be known ahead of time.
-  // see https://github.com/Agoric/agoric-3-proposals/issues/5
-  'agoric1lu9hh5vgx05hmlpfu47hukershgdxctk6l5s05',
-  'agoric15lpnq2mjsdhtztf6khp7mrsq66hyrssspy92pd',
-  'agoric1mwm224epc4l3pjcz7qsxnudcuktpynwkmnfqfp',
-];
+const { Fail } = assert;
 
 /**
  * modified copy of ../inter-protocol/price-feed-core.js
  *
  * @type {import('@agoric/deploy-script-support/src/externalTypes.js').CoreEvalBuilder}
  */
-export const priceFeedProposalBuilder = async (
+export const strictPriceFeedProposalBuilder = async (
   { publishRef, install },
-  options = {},
+  options,
 ) => {
   const {
     AGORIC_INSTANCE_NAME,
     IN_BRAND_LOOKUP,
     IN_BRAND_NAME = IN_BRAND_LOOKUP[IN_BRAND_LOOKUP.length - 1],
+    ORACLE_ADDRESSES,
   } = options;
 
-  const { GOV1ADDR, GOV2ADDR, GOV3ADDR } = process.env;
-  const oracleAddresses =
-    GOV1ADDR || GOV2ADDR || GOV3ADDR
-      ? [GOV1ADDR, GOV2ADDR, GOV3ADDR].filter(x => x)
-      : ORACLE_ADDRESSES;
-  assert(Array.isArray(oracleAddresses), 'oracleAddresses array is required');
+  const oracleAddresses = ORACLE_ADDRESSES;
+  Array.isArray(oracleAddresses) ||
+    Fail`ORACLE_ADDRESSES array is required; got ${oracleAddresses}`;
 
-  assert(AGORIC_INSTANCE_NAME, 'AGORIC_INSTANCE_NAME is required');
+  AGORIC_INSTANCE_NAME ||
+    Fail`AGORIC_INSTANCE_NAME is required; got ${AGORIC_INSTANCE_NAME}`;
 
-  assert.equal(IN_BRAND_LOOKUP[0], 'agoricNames');
-  assert(IN_BRAND_NAME, 'brandIn is required');
+  Array.isArray(IN_BRAND_LOOKUP) ||
+    Fail`IN_BRAND_NAME array is required; got ${IN_BRAND_LOOKUP}`;
 
   return harden({
     sourceSpec: '@agoric/inter-protocol/src/proposals/price-feed-proposal.js',
@@ -60,3 +52,39 @@ export const priceFeedProposalBuilder = async (
     ],
   });
 };
+
+/**
+ * @deprecated use `strictPriceFeedProposalBuilder` and specify arguments instead
+ * @type {import('@agoric/deploy-script-support/src/externalTypes.js').CoreEvalBuilder}
+ */
+export const deprecatedPriceFeedProposalBuilder = async (powers, options) => {
+  console.warn(
+    'deprecated ambient `priceFeedProposalBuilder`; use `strictPriceFeedProposalBuilder` instead',
+  );
+
+  const DEFAULT_ORACLE_ADDRESSES = [
+    // XXX These are the oracle addresses. They must be provided before the chain
+    // is running, which means they must be known ahead of time.
+    // see https://github.com/Agoric/agoric-3-proposals/issues/5
+    'agoric1lu9hh5vgx05hmlpfu47hukershgdxctk6l5s05',
+    'agoric15lpnq2mjsdhtztf6khp7mrsq66hyrssspy92pd',
+    'agoric1mwm224epc4l3pjcz7qsxnudcuktpynwkmnfqfp',
+  ];
+
+  const { GOV1ADDR, GOV2ADDR, GOV3ADDR } = process.env;
+  const governanceAddressEnv = [GOV1ADDR, GOV2ADDR, GOV3ADDR].filter(x => x);
+  const ORACLE_ADDRESSES = governanceAddressEnv.length
+    ? governanceAddressEnv
+    : DEFAULT_ORACLE_ADDRESSES;
+
+  return strictPriceFeedProposalBuilder(powers, {
+    ...options,
+    ORACLE_ADDRESSES,
+  });
+};
+
+/**
+ * @deprecated use `strictPriceFeedProposalBuilder` and specify arguments instead
+ * @type {import('@agoric/deploy-script-support/src/externalTypes.js').CoreEvalBuilder}
+ */
+export const priceFeedProposalBuilder = deprecatedPriceFeedProposalBuilder;