diff --git a/stb_image.h b/stb_image.h
index 9eedabedc..1f10ab21f 100644
--- a/stb_image.h
+++ b/stb_image.h
@@ -4885,11 +4885,12 @@ static int stbi__create_png_image(stbi__png *a, stbi_uc *image_data, stbi__uint3
             STBI_FREE(final);
             return 0;
          }
+         stbi__uint32 img_x = a->s->img_x;
          for (j=0; j < y; ++j) {
             for (i=0; i < x; ++i) {
                int out_y = j*yspc[p]+yorig[p];
                int out_x = i*xspc[p]+xorig[p];
-               memcpy(final + out_y*a->s->img_x*out_bytes + out_x*out_bytes,
+               memcpy(final + out_y*img_x*out_bytes + out_x*out_bytes,
                       a->out + (j*x+i)*out_bytes, out_bytes);
             }
          }