diff --git a/pkgs/development/ruby-modules/gem-config/default.nix b/pkgs/development/ruby-modules/gem-config/default.nix
index 724435c01ca..687abc4e0fc 100644
--- a/pkgs/development/ruby-modules/gem-config/default.nix
+++ b/pkgs/development/ruby-modules/gem-config/default.nix
@@ -22,8 +22,9 @@
 , pkgconfig , ncurses, xapian_1_2_22, gpgme, utillinux, fetchpatch, tzdata, icu, libffi
 , cmake, libssh2, openssl, mysql, darwin, git, perl, pcre, gecode_3, curl
 , msgpack, qt59, libsodium, snappy, libossp_uuid, lxc, libpcap, xorg, gtk2, buildRubyGem
-, cairo, re2, rake, gobject-introspection, gdk_pixbuf, zeromq, graphicsmagick, libcxx, file
-, libselinux ? null, libsepol ? null, libvirt
+, cairo, re2, rake, gobject-introspection, gdk_pixbuf, zeromq, czmq, graphicsmagick, libcxx
+, file, libvirt
+, libselinux ? null, libsepol ? null
 }@args:
 
 let
@@ -301,6 +302,11 @@ in
     buildInputs = [ rainbow_rake ];
   };
 
+  rbczmq = { ... }: {
+    buildInputs = [ zeromq czmq ];
+    buildFlags = [ "--with-system-libs" ];
+  };
+
   rbnacl = spec:
     if lib.versionOlder spec.version "6.0.0" then {
       postInstall = ''