--- m4/fltk.m4.orig	2014-12-13 13:46:29.000000000 +0100
+++ m4/fltk.m4	2014-12-13 14:03:44.000000000 +0100
@@ -38,7 +38,7 @@
           FLTK_LIBS=`$FLTK_CONFIG --ldflags --use-images`
           if test "x$target_mingw32" != "xyes"; then
               if test "x$target_darwin" != "xyes"; then
-                  if grep -q "lX11" <<< "$FLTK_LIBS"; then
+                  if echo "$FLTK_LIBS" | grep -q "lX11" ; then
                       FLTK_LIBS="$FLTK_LIBS";
                   else
                       FLTK_LIBS="$FLTK_LIBS -lm -lX11";