diff -r 0ac78517ada7 external/libpng-1.6.2/pngget.c
--- a/external/libpng-1.6.2/pngget.c	Sun Jun 14 17:48:43 2015 -0700
+++ b/external/libpng-1.6.2/pngget.c	Wed Jun 17 08:45:17 2015 +0200
@@ -858,8 +858,9 @@
        * if neither floating point APIs nor internal floating point arithmetic
        * are enabled.
        */
-      *width = png_fixed(png_ptr, atof(info_ptr->scal_s_width), "sCAL width");
-      *height = png_fixed(png_ptr, atof(info_ptr->scal_s_height),
+      /* https://bugzilla.libsdl.org/show_bug.cgi?id=2758 : atof->strtod */
+      *width = png_fixed(png_ptr, strtod(info_ptr->scal_s_width, NULL), "sCAL width");
+      *height = png_fixed(png_ptr, strtod(info_ptr->scal_s_height, NULL),
          "sCAL height");
       return (PNG_INFO_sCAL);
    }
@@ -877,8 +878,9 @@
        (info_ptr->valid & PNG_INFO_sCAL))
    {
       *unit = info_ptr->scal_unit;
-      *width = atof(info_ptr->scal_s_width);
-      *height = atof(info_ptr->scal_s_height);
+      /* https://bugzilla.libsdl.org/show_bug.cgi?id=2758 : atof->strtod */
+      *width = strtod(info_ptr->scal_s_width, NULL);
+      *height = strtod(info_ptr->scal_s_height, NULL);
       return (PNG_INFO_sCAL);
    }