From ce14a33e93e04c11f816e88185aca2c5e3949244 Mon Sep 17 00:00:00 2001
From: Glenn Randers-Pehrson <glennrp@gmail.com>
Date: Tue, 12 Sep 2017 19:35:34 -0400
Subject: [PATCH] Max valid hour is 23, not 24 in PNG tIME chunk

---
 coders/png.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/coders/png.c b/coders/png.c
index 0c47fe6d2..e4c15fbd8 100644
--- a/coders/png.c
+++ b/coders/png.c
@@ -8174,6 +8174,7 @@ static void write_tIME_chunk(Image *image,png_struct *ping,png_info *info,
   if (addhours < 0)
   {
     addhours+=24;
+    addminutes=-addminutes;
     day--;
   }
   hour+=addhours;
@@ -8202,7 +8203,7 @@ static void write_tIME_chunk(Image *image,png_struct *ping,png_info *info,
      hour++;
      minute-=60;
   }
-  if (hour > 24)
+  if (hour > 23)
   {
      day ++;
      hour -=24;
-- 
2.40.0