diff --git a/Makefile.am b/Makefile.am
index 77e6ec5d..2cfa015f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -237,6 +237,15 @@ libzmq_la_CPPFLAGS += ${sodium_CFLAGS}
 libzmq_la_LIBADD += ${sodium_LIBS}
 endif
 
+if USE_TWEETNACL
+libzmq_la_SOURCES += \
+    tweetnacl/src/tweetnacl.c \
+    tweetnacl/contrib/randombytes/devurandom.c
+libzmq_la_CXXFLAGS += \
+    -I$(top_builddir)/tweetnacl/contrib/randombytes \
+    -I$(top_builddir)/tweetnacl/src
+endif
+
 if HAVE_PGM
 libzmq_la_CPPFLAGS += ${pgm_CFLAGS}
 libzmq_la_LIBADD += ${pgm_LIBS}
diff --git a/configure.ac b/configure.ac
index c7c83d85..492002e6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -393,20 +393,45 @@ fi
 have_sodium_library="no"
 
 AC_ARG_WITH([libsodium], [AS_HELP_STRING([--with-libsodium],
-    [require libzmq build with libsodium. Requires pkg-config [default=no]])],
+    [require libzmq build with libsodium crypto library. Requires pkg-config [default=check]])],
     [require_libsodium_ext=$withval],
-    [require_libsodium_ext=yes])
+    [require_libsodium_ext=check])
+
+AC_ARG_WITH([tweetnacl], [AS_HELP_STRING([--with-tweetnacl],
+    [build libzmq  with bundled tweetnacl crypto library [default=no]])],
+    [require_libsodium_ext=no
+     with_tweetnacl=yes
+     AC_MSG_CHECKING(for sodium)
+     AC_MSG_RESULT(tweetnacl)],
+    [with_tweetnacl=check])
 
 # conditionally require libsodium package
 if test "x$require_libsodium_ext" != "xno"; then
-    PKG_CHECK_MODULES([sodium], [libsodium], [have_sodium_library="yes"])
+  PKG_CHECK_MODULES([sodium], [libsodium],
+    [
+      have_sodium_library=yes
+      with_tweetnacl=no
+    ],
+    [
+      if test "x$require_libsodium_ext" == "xyes"; then
+        AC_MSG_ERROR(libsodium has been requested but not found)
+      else
+        AC_MSG_RESULT([             libsodium not found, using tweetnacl])
+        have_sodium_library=no
+        with_tweetnacl=yes
+      fi
+    ])
 fi
 
 if test "x$have_sodium_library" != "xno"; then
     AC_DEFINE(HAVE_LIBSODIUM, 1, [The libsodium library is to be used.])
+elif test "x$with_tweetnacl" != "xno"; then
+    AC_DEFINE(HAVE_LIBSODIUM, 1, [Sodium is provided by tweetnacl.])
+    AC_DEFINE(HAVE_TWEETNACL, 1, [Using tweetnacl.])
 fi
 
 AM_CONDITIONAL(HAVE_SODIUM, test "x$have_sodium_library" != "xno")
+AM_CONDITIONAL(USE_TWEETNACL, test "x$with_tweetnacl" != "xno")
 
 # build using pgm
 have_pgm_library="no"