diff --git a/external.go b/external.go
index a34d5d2..f769125 100644
--- a/external.go
+++ b/external.go
@@ -12,8 +12,8 @@ import (
 
 const binaryType = "external"
 
-var localFS fs.FS
-var langFS fs.FS
+var localFS dirFS
+var langFS dirFS
 
 // When using os.DirFS, even on Windows the separator seems to be '/'.
 // func FSJoin(elem ...string) string { return filepath.Join(elem...) }
@@ -29,9 +29,23 @@ func FSJoin(elem ...string) string {
 	return strings.TrimSuffix(path, sep)
 }
 
+type dirFS string
+
+func (dir dirFS) Open(name string) (fs.File, error) {
+	return os.Open(string(dir) + "/" + name)
+}
+
+func (dir dirFS) ReadFile(name string) ([]byte, error) {
+	return os.ReadFile(string(dir) + "/" + name)
+}
+
+func (dir dirFS) ReadDir(name string) ([]fs.DirEntry, error) {
+	return os.ReadDir(string(dir) + "/" + name)
+}
+
 func loadFilesystems() {
 	log.Println("Using external storage")
 	executable, _ := os.Executable()
-	localFS = os.DirFS(filepath.Join(filepath.Dir(executable), "data"))
-	langFS = os.DirFS(filepath.Join(filepath.Dir(executable), "data", "lang"))
+	localFS = dirFS(filepath.Join(filepath.Dir(executable), "data"))
+	langFS = dirFS(filepath.Join(filepath.Dir(executable), "data", "lang"))
 }