diff --git a/.gitignore b/.gitignore
index bf05e3d5..8f2d01e2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,4 +11,5 @@ build
 stats.html
 tsconfig.build.tsbuildinfo
 .ultra.cache.json
-.nyc_output
\ No newline at end of file
+.nyc_output
+.idea
\ No newline at end of file
diff --git a/.ultraignore b/.ultraignore
new file mode 100644
index 00000000..bb947bc4
--- /dev/null
+++ b/.ultraignore
@@ -0,0 +1,2 @@
+# Used only for cache unit tests
+__tests__/**/file-to-ignore.js
\ No newline at end of file
diff --git a/__tests__/git.ts b/__tests__/git.ts
index 0ed7e879..20959fec 100644
--- a/__tests__/git.ts
+++ b/__tests__/git.ts
@@ -41,15 +41,19 @@ test("getGitFiles", async () => {
   expect(files["__tests__/workspace/apps/app2/package.json"]).toMatch(
     /^[a-z0-9]*$/u
   )
+  expect(files["__tests__/workspace/apps/app1/file-to-ignore.js"]).toMatch(
+    /^[a-z0-9]*$/u
+  )
   expect(files[""]).toMatch(/^\d+\.\d+$/u)
 
-  expect(Object.keys(files)).toHaveLength(3)
+  expect(Object.keys(files)).toHaveLength(4)
 })
 
 test("cache", async () => {
   const files = f(await cache.getFiles(path.resolve(workspaceRoot, "apps")))
   expect(files["app1/package.json"]).toMatch(/^[a-z0-9]*$/u)
   expect(files["app2/package.json"]).toMatch(/^[a-z0-9]*$/u)
+  expect(files["app1/file-to-ignore.js"]).toBeUndefined()
   expect(Object.keys(files)).toHaveLength(2)
   expect(cache.cache.size).not.toBe(0)
   await cache.getFiles(path.resolve(workspaceRoot, "apps"))
diff --git a/__tests__/workspace/apps/app1/file-to-ignore.js b/__tests__/workspace/apps/app1/file-to-ignore.js
new file mode 100644
index 00000000..45a202a6
--- /dev/null
+++ b/__tests__/workspace/apps/app1/file-to-ignore.js
@@ -0,0 +1 @@
+export const FOO = 'foo'
diff --git a/package.json b/package.json
index 72269121..1acde00d 100644
--- a/package.json
+++ b/package.json
@@ -118,6 +118,7 @@
     "cross-spawn": "^7.0.3",
     "fast-glob": "^3.2.5",
     "globrex": "^0.1.2",
+    "ignore": "^5.1.8",
     "json5": "^2.2.0",
     "micro-memoize": "^4.0.9",
     "npm-run-path": "4.0.1",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index efb53c73..39aab9f0 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -4,6 +4,7 @@ dependencies:
   cross-spawn: 7.0.3
   fast-glob: 3.2.5
   globrex: 0.1.2
+  ignore: 5.1.8
   json5: 2.2.0
   micro-memoize: 4.0.9
   npm-run-path: 4.0.1
@@ -4312,7 +4313,6 @@ packages:
     resolution:
       integrity: sha512-cyFDKrqc/YdcWFniJhzI42+AzS+gNwmUzOSFcRCQYwySuBBBy/KjuxWLZ/FHEH6Moq1NizMOBWyTcv8O4OZIMg==
   /ignore/5.1.8:
-    dev: true
     engines:
       node: '>= 4'
     resolution:
@@ -8921,6 +8921,7 @@ specifiers:
   fast-glob: ^3.2.5
   globrex: ^0.1.2
   husky: 5.1.1
+  ignore: ^5.1.8
   jest: 26.6.3
   json5: ^2.2.0
   markdownlint-cli: 0.26.0
diff --git a/src/git.ts b/src/git.ts
index cc456548..18353b2d 100644
--- a/src/git.ts
+++ b/src/git.ts
@@ -1,6 +1,7 @@
 import { exec } from "child_process"
 import fs from "fs"
 import path from "path"
+import ignore, { Ignore } from "ignore"
 import { findUp } from "./package"
 import { HASH_FILE } from "./options"
 
@@ -10,6 +11,18 @@ type GitFiles = Record<string, string>
 
 export class NoGitError extends Error {}
 
+function getUltraIgnore(root: string): Ignore {
+  const ultraIgnorePath = path.resolve(root, ".ultraignore")
+  const ultraIgnoreExists = fs.existsSync(ultraIgnorePath)
+
+  const ultraIgnore = ignore()
+  if (ultraIgnoreExists) {
+    ultraIgnore.add(fs.readFileSync(ultraIgnorePath).toString())
+  }
+
+  return ultraIgnore
+}
+
 export function parseFiles(data: string, root: string): GitFiles {
   const ret: GitFiles = {}
   data.split("\n").forEach((line) => {
@@ -36,12 +49,8 @@ export function parseFiles(data: string, root: string): GitFiles {
 
 export async function getGitFiles(root: string): Promise<GitFiles> {
   return new Promise((resolve, reject) => {
-    const ultraIgnoreExists = fs.existsSync(path.resolve(root, ".ultraignore"))
-    const lsFiles = `git ls-files --full-name -s -d -c -m -o ${
-      ultraIgnoreExists ? "-X .ultraignore" : ""
-    } --directory -t`
     exec(
-      lsFiles,
+      "git ls-files --full-name -s -d -c -m -o --directory -t",
       { cwd: root, maxBuffer: 1024 * 1024 * 1024 },
       (error, stdout) => {
         if (error) return reject(error)
@@ -68,6 +77,8 @@ class FilesCache {
     const files = this.cache.get(root) || {}
     const ret: GitFiles = {}
 
+    const ultraIgnore = getUltraIgnore(root)
+
     Object.entries(files)
       .filter(([file]) => {
         const filePath = path.resolve(root, file)
@@ -75,6 +86,7 @@ class FilesCache {
           filePath == directory || filePath.startsWith(directory + path.sep)
         )
       })
+      .filter(([file]) => !ultraIgnore.ignores(file))
       .map(([file, hash]) => [
         path.relative(directory, path.resolve(root, file)),
         hash,