diff --git a/2021/4/data b/2021/4/data
index ba441b7..25caf6c 100644
--- a/2021/4/data
+++ b/2021/4/data
@@ -599,3 +599,4 @@
 68 36  4 24 71
 43 31 60 19 95
 52 55 13 83 78
+
diff --git a/2021/4/main.py b/2021/4/main.py
index eb5937c..dcd7c6b 100644
--- a/2021/4/main.py
+++ b/2021/4/main.py
@@ -56,6 +56,9 @@ with open('data', 'r') as fp:
         else:
             # add the next array of numbers to the temporary board object
             temp_board.append(line.strip().split())
+    if(len(temp_board)):
+        print('ERROR: You must have an empty line at the end of your data.')
+        exit()
 
 winning_number,winning_board_index = FindWinner(numbers)
 print('Winning Number:', winning_number, ', Winning Board Index: ', winning_board_index)