diff --git a/examples/sixdraw.c b/examples/sixdraw.c
index 385aac7..484fddd 100644
--- a/examples/sixdraw.c
+++ b/examples/sixdraw.c
@@ -29,7 +29,6 @@
 #  include "config.h"
 #endif  // HAVE_CONFIG_H
 
-#include <signal.h>
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -140,8 +139,8 @@ get_winsize(struct sixdraw_ctx *ctx)
     ctx->rows = ws.ws_row;
     ctx->ch_width = ws.ws_xpixel / ws.ws_col;
     ctx->ch_height = ws.ws_ypixel / ws.ws_row;
-    ctx->canvas_width = ws.ws_xpixel - ctx->ch_width;
-    ctx->canvas_height = ws.ws_ypixel - ctx->ch_height * 3;
+    ctx->canvas_width = ctx->ch_width * ws.ws_col;
+    ctx->canvas_height = ctx->ch_height * ws.ws_row - ctx->ch_height * 2;
     return true;
 }
 
@@ -377,6 +376,7 @@ draw(struct sixdraw_ctx *ctx)
     while (true) {
         switch (ctlseqs_read(ctx->reader, ctx->matcher, -1)) {
             case 2:  // CTLSEQS_RESP_SGR_MOUSE
+                // Pixel coordinates start at 1 instead of 0.
                 print_sixel_dot(ctx, result[1].num - 1, result[2].num - 1);
                 break;
             case CTLSEQS_NOSEQ: