diff --git a/Makefile.am b/Makefile.am
index 1f10764..8f70ecf 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -6,8 +6,8 @@ man8_MANS = openconnect.8
 
 openconnect_SOURCES = xml.c main.c dtls.c cstp.c mainloop.c tun.c
 
-openconnect_CFLAGS = $(OPENSSL_CFLAGS) $(LIBXML2_CFLAGS) $(LIBPROXY_CFLAGS)
-openconnect_LDADD = libopenconnect.la $(OPENSSL_LIBS) $(LIBXML2_LIBS) $(LIBPROXY_LIBS)
+openconnect_CFLAGS = $(OPENSSL_CFLAGS) $(LIBXML2_CFLAGS) $(LIBPROXY_CFLAGS) $(ZLIB_CFLAGS)
+openconnect_LDADD = libopenconnect.la $(OPENSSL_LIBS) $(LIBXML2_LIBS) $(LIBPROXY_LIBS) $(ZLIB_LIBS)
 
 libopenconnect_la_SOURCES = ssl.c http.c version.c auth.c library.c
 libopenconnect_la_CFLAGS = $(OPENSSL_CFLAGS) $(LIBXML2_CFLAGS) $(LIBPROXY_CFLAGS)
diff --git a/configure.ac b/configure.ac
index 6dd0ec6..753474d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -20,6 +20,7 @@ AC_ARG_WITH([openssl],
 AC_PROG_LIBTOOL
 
 PKG_CHECK_MODULES(LIBXML2, libxml-2.0)
+PKG_CHECK_MODULES(ZLIB, zlib)
 
 libproxy_hdr=no
 AC_CHECK_HEADER([libproxy.h],