diff --git a/day05/day05-2.py b/day05/day05-2.py
index 149b3da..9de761a 100644
--- a/day05/day05-2.py
+++ b/day05/day05-2.py
@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 import re
+import copy
 
 test = ("""    [D]    
 [N] [C]    
@@ -38,7 +39,8 @@ def rearrange_stacks( input ):
     return stack
 
 def read_stacks_top( stacks ):
-    top = list(map(list.pop, stacks))
+    stacks_c = copy.deepcopy(stacks)
+    top = list(map(list.pop, stacks_c))
     print("".join(top))
 
 
diff --git a/day05/day05.py b/day05/day05.py
index 417b920..90389ed 100644
--- a/day05/day05.py
+++ b/day05/day05.py
@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 import re
+import copy
 
 test = ("""    [D]    
 [N] [C]    
@@ -38,7 +39,8 @@ def rearrange_stacks( input ):
     return stack
 
 def read_stacks_top( stacks ):
-    top = list(map(list.pop, stacks))
+    stacks_c = copy.deepcopy(stacks)
+    top = list(map(list.pop, stacks_c))
     print("".join(top))