diff --git a/src/git-command-manager.ts b/src/git-command-manager.ts
index 4f2b792..b9438a9 100644
--- a/src/git-command-manager.ts
+++ b/src/git-command-manager.ts
@@ -114,11 +114,7 @@ export class GitCommandManager {
     }
 
     args.push('--progress', '--no-recurse-submodules')
-    if (
-      utils.fileExistsSync(
-        realpathSync(path.join(this.workingDirectory, '.git', 'shallow'))
-      )
-    ) {
+    if (await this.isShallow()) {
       args.push('--unshallow')
     }
 
@@ -164,6 +160,11 @@ export class GitCommandManager {
     return this.workingDirectory
   }
 
+  async isShallow(): Promise<boolean> {
+    const result = await this.revParse('', ['--is-shallow-repository'])
+    return result === 'true'
+  }
+
   async hasDiff(options?: string[]): Promise<boolean> {
     const args = ['diff', '--quiet']
     if (options) {