diff --git a/twrp-functions.hpp b/twrp-functions.hpp
index 8531c09..4040d2e 100644
--- a/twrp-functions.hpp
+++ b/twrp-functions.hpp
@@ -48,7 +48,7 @@
 	static int drop_caches(void); //drop linux cache memory
 	static int Check_su_Perms(void); // check perms and owner of su binary in various locations
 	static bool Fix_su_Perms(void); // sets proper permissions for su binaries and superuser apk
-	static int tw_chmod(string fn, string mode); // chmod function that converts a 4 char string into st_mode automatically
+	static int tw_chmod(const string& fn, const string& mode); // chmod function that converts a 3 or 4 char string into st_mode automatically
 	static bool Install_SuperSU(void); // Installs su binary and apk and sets proper permissions
 	static vector<string> split_string(const string &in, char del, bool skip_empty);
 	static int Get_File_Type(string fn); // Determines file type, 0 for unknown, 1 for gzip, 2 for OAES encrypted