diff --git a/day_03/program.py b/day_03/program.py
index bd5f517..519242a 100755
--- a/day_03/program.py
+++ b/day_03/program.py
@@ -12,7 +12,7 @@ def get_lines(filename: str) -> list:
 
 def part1_get_result_sum(lines: list) -> int:
     result_sum = 0
-    pattern = re.compile(r"mul\((\d+),(\d+)\)")
+    pattern = re.compile(r"mul\((\d{1,3}),(\d{1,3})\)")
     for line in lines:
         matches = re.findall(pattern, line)
         for match in matches: