diff --git a/day4/p2.c b/day4/p2.c
index dffbab8..9756d00 100644
--- a/day4/p2.c
+++ b/day4/p2.c
@@ -6,7 +6,8 @@
 #include <stdbool.h>
 
 
-#define STACK_SZ 256
+#define STACK_SZ UINT8_MAX+1
+typedef uint8_t stackpointer_t;
 
 int32_t parse_number(char *end);
 
@@ -30,7 +31,7 @@ int main(int argc, char **argv) {
     char *colon_pos = NULL, *pipe_pos = NULL;
 
     uint64_t stack[STACK_SZ] = {0};
-    uint8_t stack_pos = 0;
+    stackpointer_t stack_pos = 0;
 
     while (getline(&line, &line_length, input) != -1) {
         colon_pos = strchr(line, ':');