diff --git a/tools/tp.py b/tools/tp.py
index c16ffd92f76..21c07bf69d1 100644
--- a/tools/tp.py
+++ b/tools/tp.py
@@ -450,12 +450,13 @@ def calculate_rel_progress(build_path: Path, matching: bool, format: str, asm_fi
     start = time.time()
     from collections import defaultdict
 
+    str_asm_rel = f"asm{os.path.sep}rel{os.path.sep}"
     range_dict = defaultdict(list)
     for file, range in zip(asm_files, ranges):
         str_file = str(file)
-        if not str_file.startswith("asm/rel/"):
+        if not str_file.startswith(str_asm_rel):
             continue
-        rel = str_file.split("/")[-3]
+        rel = str_file.split(os.path.sep)[-3]
         range_dict[rel].append(range[1] - range[0])
 
     end = time.time()