diff --git a/packages/baseline-browser-mapping/src/scripts/baseline-browser-versions.ts b/packages/baseline-browser-mapping/src/scripts/baseline-browser-versions.ts
index 16542dc86f6..4d769cb10c0 100644
--- a/packages/baseline-browser-mapping/src/scripts/baseline-browser-versions.ts
+++ b/packages/baseline-browser-mapping/src/scripts/baseline-browser-versions.ts
@@ -1,5 +1,8 @@
-import bcdBrowsers from "@mdn/browser-compat-data" assert { type: "json" };
-import otherBrowsers from "../data/downstream-browsers.json" assert { type: "json" };
+import { createRequire } from "module";
+const require = createRequire(import.meta.url);
+
+const bcdBrowsers = require("@mdn/browser-compat-data");
+const otherBrowsers = require("../data/downstream-browsers.json");
 
 const bcdCoreBrowserNames: string[] = [
   "chrome",
@@ -11,9 +14,42 @@ const bcdCoreBrowserNames: string[] = [
   "safari_ios",
 ];
 
-const coreBrowserData = Object.entries(bcdBrowsers.browsers).filter(
-  ([browserName, browserData]) => bcdCoreBrowserNames.includes(browserName),
-);
+type BrowserData = {
+  [key: string]: {
+    releases: {
+      [key: string]: {
+        status: string;
+        release_date?: string;
+      };
+    };
+  };
+};
+
+interface Browser {
+  name: string;
+  releases: {
+    [version: string]: {
+      status: string;
+      release_date?: string;
+      engine?: string;
+      engine_version?: string;
+    };
+  };
+}
+
+interface BrowserVersion {
+  browser: string;
+  version: string;
+  release_date: string;
+  engine: string | null;
+  engine_version: string | null;
+}
+
+const coreBrowserData: [string, Browser][] = Object.entries(
+  bcdBrowsers.browsers as BrowserData,
+).filter(([browserName, browserData]) =>
+  bcdCoreBrowserNames.includes(browserName),
+) as [string, Browser][];
 
 const bcdDownstreamBrowserNames: string[] = [
   "webview_android",
@@ -21,24 +57,19 @@ const bcdDownstreamBrowserNames: string[] = [
   "opera_android",
   "opera",
 ];
-
-const downstreamBrowserData = [
-  ...Object.entries(bcdBrowsers.browsers).filter(([browserName, browserData]) =>
-    bcdDownstreamBrowserNames.includes(browserName),
-  ),
-  ...Object.entries(otherBrowsers.browsers),
+const downstreamBrowserData: [string, Browser][] = [
+  ...(Object.entries(bcdBrowsers.browsers as BrowserData).filter(
+    ([browserName, browserData]) =>
+      bcdDownstreamBrowserNames.includes(browserName),
+  ) as [string, Browser][]),
+  ...(Object.entries(otherBrowsers.browsers as BrowserData) as [
+    string,
+    Browser,
+  ][]),
 ];
 
 const acceptableStatuses: string[] = ["current", "esr", "retired", "unknown"];
 
-interface BrowserVersion {
-  browser: string;
-  version: string;
-  release_date: string;
-  engine: string | null;
-  engine_version: string | null;
-}
-
 const compareVersions = (
   incomingVersionString: string,
   previousVersionString: string,
@@ -103,9 +134,7 @@ const getCoreVersionsByDate = (
         return true;
       })
       .sort((a, b) => {
-        {
-          return compareVersions(a[0], b[0]);
-        }
+        return compareVersions(a[0], b[0]);
       });
     for (let i = 1; i < sortedVersions.length; i++) {
       const thisVersion = sortedVersions[i];
@@ -161,6 +190,7 @@ const getDownstreamBrowsers = (
   let downstreamArray: BrowserVersion[] = new Array();
 
   downstreamBrowserData.forEach(([browserName, browserData]) => {
+    if (!browserData.releases) return;
     let sortedAndFilteredVersions = Object.entries(browserData.releases)
       .filter(([versionNumber, versionData]) => {
         if (!versionData.engine) {
@@ -170,7 +200,8 @@ const getDownstreamBrowsers = (
           return false;
         }
         if (
-          parseInt(versionData.engine_version) < parseInt(minimumChromeVersion)
+          versionData.engine_version &&
+          parseInt(versionData.engine_version) < parseInt(minimumChromeVersion!)
         ) {
           return false;
         }
@@ -187,9 +218,9 @@ const getDownstreamBrowsers = (
         downstreamArray.push({
           browser: browserName,
           version: versionNumber,
-          release_date: versionData.release_date,
-          engine: versionData.engine,
-          engine_version: versionData.engine_version,
+          release_date: versionData.release_date ?? "unknown",
+          engine: versionData.engine ?? null,
+          engine_version: versionData.engine_version ?? null,
         });
         if (minOnly) {
           break;
diff --git a/packages/baseline-browser-mapping/tsconfig.json b/packages/baseline-browser-mapping/tsconfig.json
index 8da82e0b5ec..8c858ebe134 100644
--- a/packages/baseline-browser-mapping/tsconfig.json
+++ b/packages/baseline-browser-mapping/tsconfig.json
@@ -11,5 +11,5 @@
     "strict": true,
     "noUncheckedIndexedAccess": true
   },
-  "include": ["./src"]
+  "include": ["./src", "./src/data/downstream-browsers.json"]
 }