diff --git a/tools/fs/files.ts b/tools/fs/files.ts
index b91a5a6799..9980d767ff 100644
--- a/tools/fs/files.ts
+++ b/tools/fs/files.ts
@@ -404,6 +404,8 @@ export function treeHash(root: string, optionsParams: {
       }
       hash.update('file ' + JSON.stringify(relativePath) + ' ' +
                   stat.size + ' ' + fileHash(absPath) + '\n');
+
+      // @ts-ignore
       if (stat.mode & 0o100) {
         hash.update('exec\n');
       }
@@ -537,6 +539,8 @@ export function cp_r(from: string, to: string, options: {
       // owner. (This mode will be modified by umask.) We don't copy the
       // mode *directly* because this function is used by 'meteor create'
       // which is copying from the read-only tools tree into a writable app.
+
+      // @ts-ignore
       mode: (stat.mode & 0o100) ? 0o777 : 0o666,
     });
 
@@ -1698,6 +1702,8 @@ export function copyFile(from: string, to: string, flags = 0) {
     // modified by umask.) We don't copy the mode *directly* because this function
     // is used by 'meteor create' which is copying from the read-only tools tree
     // into a writable app.
+
+    // @ts-ignore
     chmod(to, (stat.mode & 0o100) ? 0o777 : 0o666);
   }
 }
diff --git a/tools/fs/safe-watcher.ts b/tools/fs/safe-watcher.ts
index c90fa56c18..909dfa6b26 100644
--- a/tools/fs/safe-watcher.ts
+++ b/tools/fs/safe-watcher.ts
@@ -1,4 +1,4 @@
-import { FSWatcher, Stats } from "fs";
+import { FSWatcher, Stats, BigIntStats } from "fs";
 import { Profile } from "../tool-env/profile";
 import {
   statOrNull,
@@ -89,7 +89,7 @@ function acquireWatcher(absPath: string, callback: EntryCallback) {
 }
 
 function startNewWatcher(absPath: string): Entry {
-  let stat: Stats | null = null;
+  let stat: Stats | BigIntStats | null = null;
 
   if (DEDUPLICATE_BY_INO) {
     stat = statOrNull(absPath);
diff --git a/tools/fs/watch.ts b/tools/fs/watch.ts
index f473840331..970d38be09 100644
--- a/tools/fs/watch.ts
+++ b/tools/fs/watch.ts
@@ -1,4 +1,4 @@
-import { Stats, FSWatcher, Dirent } from "fs";
+import { Stats, BigIntStats, FSWatcher, Dirent } from "fs";
 import * as files from "./files";
 import * as safeWatcher from "./safe-watcher";
 import { createHash } from "crypto";
@@ -351,7 +351,7 @@ function readAndStatDirectory(absPath: string) {
   // Add slashes to the end of directories.
   const contentsWithSlashes: string[] = [];
   contents.forEach(entry => {
-    let stat: Dirent | Stats | null = entry;
+    let stat: Dirent | Stats | BigIntStats | null = entry;
     let name = entry.name;
 
     if (entry.isSymbolicLink()) {
@@ -428,7 +428,7 @@ export class Watcher {
     watcher: safeWatcher.SafeWatcher | null;
     // Undefined until we stat the file for the first time, then null
     // if the file is observed to be missing.
-    lastStat?: Stats | null
+    lastStat?: Stats | BigIntStats | null
   }> = Object.create(null);
 
   constructor(options: {
diff --git a/tools/isobuild/resolver.ts b/tools/isobuild/resolver.ts
index 0092f20fb4..c84c56f29e 100644
--- a/tools/isobuild/resolver.ts
+++ b/tools/isobuild/resolver.ts
@@ -14,7 +14,7 @@ import {
   convertToOSPath,
   convertToPosixPath,
 } from "../fs/files";
-import { Stats } from "fs";
+import { Stats, BigIntStats } from "fs";
 import { wrap } from "optimism";
 import {
   optimisticStatOrNull,
@@ -42,7 +42,7 @@ export type ResolverOptions = {
 }
 
 export type Resolution = {
-  stat: Stats;
+  stat: Stats | BigIntStats;
   path: string;
   packageJsonMap?: Record<string, Record<string, any>>;
   id?: string;
@@ -63,7 +63,7 @@ export default class Resolver {
   private nodeModulesPaths: string[];
   private mainFields: string[];
 
-  public statOrNull = optimisticStatOrNull as (path: string) => Stats | null;
+  public statOrNull = optimisticStatOrNull as (path: string) => Stats | BigIntStats | null;
 
   constructor({
     sourceRoot,