diff --git a/xorriso/configure_ac.txt b/xorriso/configure_ac.txt
index c941899c..563d90a5 100644
--- a/xorriso/configure_ac.txt
+++ b/xorriso/configure_ac.txt
@@ -368,6 +368,7 @@ dnl The empty parameter after "compressBound" causes -lz.
     ZLIB_DEF=yes
     AC_CHECK_HEADER(zlib.h, AC_CHECK_LIB(z, compressBound, , ZLIB_DEF= ), ZLIB_DEF= )
 else
+    echo "disabled use of zlib"
     ZLIB_DEF=
 fi
 if test x$ZLIB_DEF = xyes