...

diff --git a/coders/png.c b/coders/png.c
index 96b9c65f0662f6a5eb31238a5222803ec46150c9..cc9693fa4114bc87ba96c9faf55d09dc19828092 100644 (file)
--- a/coders/png.c
+++ b/coders/png.c
@@ -4795,7 +4795,8 @@ static Image *ReadOneJNGImage(MngInfo *mng_info,
       {
         /* Copy chunk data to alpha_image->blob */
 
-        if (alpha_image != NULL && image_info->ping == MagickFalse)
+        if ((alpha_image != NULL) && (image_info->ping == MagickFalse) &&
+            (length != 0))
           {
             if (logging != MagickFalse)
               (void) LogMagickEvent(CoderEvent,GetMagickModule(),