diff --git a/day4/p2.c b/day4/p2.c
index 14378a8..dffbab8 100644
--- a/day4/p2.c
+++ b/day4/p2.c
@@ -23,13 +23,13 @@ int main(int argc, char **argv) {
 		return -1;
 	}
 
-    uint32_t total_copies = 0;
+    uint64_t total_copies = 0;
 
     size_t winning_numbers_len = 0;
     int8_t *winning_numbers = NULL;
     char *colon_pos = NULL, *pipe_pos = NULL;
 
-    uint32_t stack[STACK_SZ] = {0};
+    uint64_t stack[STACK_SZ] = {0};
     uint8_t stack_pos = 0;
 
     while (getline(&line, &line_length, input) != -1) {
@@ -45,7 +45,7 @@ int main(int argc, char **argv) {
             winning_numbers[i] = parse_number((char *)(wl_pos-1));
         }
 
-        uint32_t card_copies = 1 + stack[stack_pos++];
+        uint64_t card_copies = 1 + stack[stack_pos++];
 
         total_copies += card_copies;
 
@@ -70,7 +70,7 @@ int main(int argc, char **argv) {
 
     free(winning_numbers);
 
-    printf("%d\n", total_copies);
+    printf("%lu\n", total_copies);
 
     return 0;
 }