diff --git externals/stb/stb_image.h externals/stb/stb_image.h
index 5e807a0a6..725d0ec9e 100644
--- externals/stb/stb_image.h
+++ externals/stb/stb_image.h
@@ -5079,7 +5079,7 @@ static void stbi__de_iphone(stbi__png *z)
 static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp)
 {
    stbi_uc palette[1024], pal_img_n=0;
-   stbi_uc has_trans=0, tc[3]={0};
+   stbi_uc has_trans=0, tc[4]={0};
    stbi__uint16 tc16[3];
    stbi__uint32 ioff=0, idata_limit=0, i, pal_len=0;
    int first=1,k,interlace=0, color=0, is_iphone=0;
@@ -5163,7 +5163,7 @@ static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp)
                if (z->depth == 16) {
                   for (k = 0; k < s->img_n; ++k) tc16[k] = (stbi__uint16)stbi__get16be(s); // copy the values as-is
                } else {
-                  for (k = 0; k < s->img_n; ++k) tc[k] = (stbi_uc)(stbi__get16be(s) & 255) * stbi__depth_scale_table[z->depth]; // non 8-bit images will be larger
+                  for (k = 0; k < s->img_n && k < 4; ++k) tc[k] = (stbi_uc)(stbi__get16be(s) & 255) * stbi__depth_scale_table[z->depth]; // non 8-bit images will be larger
                }
             }
             break;