From d70a72fddade92be4353a4184d05094e30f0d2d5 Mon Sep 17 00:00:00 2001
From: Michael R Sweet <msweet@msweet.org>
Date: Thu, 1 Jan 2026 09:57:43 -0500
Subject: [PATCH] Update prerequisites.

---
 README.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 2c871df..8a5ed4d 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,8 @@ PDFio requires the following to build the software:
 
 - A C99 compiler such as Clang, GCC, or MS Visual C
 - A POSIX-compliant `make` program
-- ZLIB (<https://www.zlib.net>) 1.1 or higher
+- LIBPNG (1.6 or later) for full PNG image support (optional)
+- ZLIB (1.1 or later)
 
 IDE files for Xcode (macOS/iOS) and Visual Studio (Windows) are also provided.