diff -up EMBOSS-6.6.0/configure.in.system-zlib EMBOSS-6.6.0/configure.in
--- EMBOSS-6.6.0/configure.in.system-zlib	2015-10-30 09:32:02.595043840 -0400
+++ EMBOSS-6.6.0/configure.in	2015-10-30 09:32:48.225796757 -0400
@@ -811,6 +811,7 @@ AC_ARG_ENABLE([systemlibs],
 if test "x${enable_systemlibs}" = "xyes" ; then
    AC_CHECK_LIB(pcre, pcre_compile)
    AC_CHECK_LIB(expat, XML_ParserCreate)
+   AC_CHECK_LIB(z, compress)
 fi
 AM_CONDITIONAL([ESYSTEMLIBS], [test "x${enable_systemlibs}" = "xyes"])
 
@@ -964,7 +965,6 @@ AC_CONFIG_FILES([Makefile
                  ajax/core/Makefile
                  ajax/ensembl/Makefile
                  ajax/graphics/Makefile
-                 ajax/zlib/Makefile
                  doc/Makefile
                  doc/manuals/Makefile
                  doc/programs/Makefile