diff -u -r ../zeromq-4.2.2/configure.ac ./configure.ac
--- ../zeromq-4.2.2/configure.ac	2017-02-18 19:05:37.000000000 +0100
+++ ./configure.ac	2017-03-23 10:31:34.501893021 +0100
@@ -653,17 +653,6 @@
     AC_SUBST(pkg_config_defines, "")
 fi
 
-PKG_CHECK_MODULES(LIBUNWIND, [libunwind],
-    [
-        AC_DEFINE(HAVE_LIBUNWIND, 1, [The libunwind library is to be used])
-        AC_SUBST([LIBUNWIND_CFLAGS])
-        AC_SUBST([LIBUNWIND_LIBS])
-        AC_CHECK_LIB([dl], [dladdr])
-    ],
-    [
-        AC_MSG_WARN([Cannot find libunwind])
-    ])
-
 # Subst LIBZMQ_EXTRA_CFLAGS & CXXFLAGS & LDFLAGS
 AC_SUBST(LIBZMQ_EXTRA_CFLAGS)
 AC_SUBST(LIBZMQ_EXTRA_CXXFLAGS)