diff --git a/MSET9_installer_script/mset9.py b/MSET9_installer_script/mset9.py
index 386a639..236e236 100644
--- a/MSET9_installer_script/mset9.py
+++ b/MSET9_installer_script/mset9.py
@@ -168,7 +168,10 @@ if osver == "Darwin":
 			if dirname.startswith(tmpprefix):
 				dirpath = f"{systmp}/{dirname}"
 				script = f"{dirpath}/mset9.py"
-				if os.path.exists(script) and os.stat(script).st_mtime > os.stat(thisfile).st_mtime:
+				tmp_st = os.stat(script)
+				this_st = os.stat(thisfile)
+				# hope file size is enough fix... checksum is a bit heavy i assume
+				if os.path.exists(script) and tmp_st.st_mtime > this_st.st_mtime and tmp_st.st_size == this_st.st_size:
 					tmpdir = dirpath
 					break
 				else: