diff --git a/pkgs/development/ruby-modules/gem-config/default.nix b/pkgs/development/ruby-modules/gem-config/default.nix
index dd4ae725095d..05be9090c84a 100644
--- a/pkgs/development/ruby-modules/gem-config/default.nix
+++ b/pkgs/development/ruby-modules/gem-config/default.nix
@@ -21,7 +21,7 @@
 , libiconv, postgresql, v8_3_16_14, clang, sqlite, zlib, imagemagick
 , pkgconfig , ncurses, xapian, gpgme, utillinux, fetchpatch, tzdata, icu, libffi
 , cmake, libssh2, openssl, mysql, darwin, git, perl, gecode_3, curl
-, libmsgpack
+, libmsgpack, qt5Full
 }:
 
 let
@@ -29,6 +29,10 @@ let
 in
 
 {
+  capybara-webkit = attrs: {
+    buildInputs = [ qt5Full ];
+  };
+
   charlock_holmes = attrs: {
     buildInputs = [ which icu zlib ];
   };