git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@6450 
c3d73ce0-8a6f-49c7-b76d-
6d57e0e08775
 #define wxUSE_LIBPNG 1
 EOF
 
 #define wxUSE_LIBPNG 1
 EOF
 
-      if test "$wxUSE_ZLIB" != "sys" ; then
+      if test "$wxUSE_LIBPNG" = "sys" -a "$wxUSE_ZLIB" != "sys" ; then
     echo "configure: warning: --with-libpng=sys doesn't work without --with-zlib=sys, will compile the built-in libpng instead" 1>&2
     wxUSE_LIBPNG=yes
   fi
     echo "configure: warning: --with-libpng=sys doesn't work without --with-zlib=sys, will compile the built-in libpng instead" 1>&2
     wxUSE_LIBPNG=yes
   fi