diff --git a/aoc.py b/aoc.py
index ed2cc38..db845b0 100644
--- a/aoc.py
+++ b/aoc.py
@@ -133,7 +133,7 @@ def printSolution(day, part, solution, test=None, test_case=0, exec_time=None):
         print("Solution to day %s, part %s: %s%s" % (day, part, solution, time_output))
 
 
-def splitLine(line, split_char=',', return_type=None):
+def splitLine(line, split_char: str = ',', return_type: Union[Type, List[Type]] = None):
     if split_char:
         line = line.split(split_char)