Index: aocutils.c
==================================================================
--- aocutils.c
+++ aocutils.c
@@ -1,24 +1,18 @@
-#include <stbool.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include "aocutils.h"
 
-struct TextGrid {
-    unsigned rows, cols;
-    char *data; // may have '\n' at end of rows
-};
-
 bool TGvalid(struct TextGrid *tg, unsigned row, unsigned col) {
     if (row >= tg->rows) return false;
     if (col >= tg->cols) return false;
     return true;
 }
 char *TGcharptr(struct TextGrid *tg, unsigned row, unsigned col) {
-    if (row >= tg->rows) return NULL;
-    if (col >= tg->cols) return NULL;
-    return data + (row * tg->cols) + col;
+    if (!TGvalid(tg, row, col)) return NULL;
+    return tg->data + (row * tg->cols) + col;
 }
 
 // TODO: rewrite this shit
 size_t linearize2d(unsigned width, unsigned row, unsigned col) {
     return (row * width) + col;