diff --git a/school_center.py b/school_center.py
index 271e2f0..9140f8f 100644
--- a/school_center.py
+++ b/school_center.py
@@ -207,8 +207,8 @@ def is_allocated(scode1: str, scode2: str) -> bool:
 
 OUTPUT_DIR = 'results/'
 create_dir(OUTPUT_DIR)  # Create the output directory if not exists
-with open('{}school-center-distance.tsv'.format(OUTPUT_DIR), 'w', encoding='utf-8') as intermediate_file, \
-        open(OUTPUT_DIR + args.output, 'w', encoding='utf-8') as a_file:
+with open(os.path.join(OUTPUT_DIR, 'school-center-distance.tsv'), 'w', encoding='utf-8') as intermediate_file, \
+        open(os.path.join(OUTPUT_DIR, args.output), 'w', encoding='utf-8') as a_file:
     writer = csv.writer(intermediate_file, delimiter="\t")
     writer.writerow(["scode", 
                      "s_count",