diff --git a/CHANGELOG.md b/CHANGELOG.md
index 73ad1d56b..25f8a0736 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@
 - **decompress:** Exclude '*.nsis' that may cause error ([#5294](https://github.com/ScoopInstaller/Scoop/issues/5294))
 - **autoupdate:** Fix file hash extraction ([#5295](https://github.com/ScoopInstaller/Scoop/issues/5295))
 - **shortcuts:** Output correctly formatted path ([#5333](https://github.com/ScoopInstaller/Scoop/issues/5333))
+- **core:** Fix `is_in_dir` under Unix ([#5391](https://github.com/ScoopInstaller/Scoop/issues/5391))
 
 ### Code Refactoring
 
diff --git a/lib/install.ps1 b/lib/install.ps1
index cdbfdf1a7..5b5270411 100644
--- a/lib/install.ps1
+++ b/lib/install.ps1
@@ -632,7 +632,7 @@ function cookie_header($cookies) {
 function is_in_dir($dir, $check) {
     $check = "$(fullpath $check)"
     $dir = "$(fullpath $dir)"
-    $check -match "^$([regex]::escape("$dir"))(\\|`$)"
+    $check -match "^$([regex]::Escape("$dir"))([/\\]|`$)"
 }
 
 function ftp_file_size($url) {