diff --git a/pkgs/development/ruby-modules/gem-config/default.nix b/pkgs/development/ruby-modules/gem-config/default.nix
index 1a95520b9273..9f2e8dbfcd11 100644
--- a/pkgs/development/ruby-modules/gem-config/default.nix
+++ b/pkgs/development/ruby-modules/gem-config/default.nix
@@ -26,7 +26,7 @@
 , file, libvirt, glib, vips, taglib, libopus, linux-pam, libidn, protobuf, fribidi, harfbuzz
 , bison, flex, pango, python3, patchelf, binutils, freetds, wrapGAppsHook, atk
 , bundler, libsass, libexif, libselinux, libsepol, shared-mime-info, libthai, libdatrie
-, CoreServices, DarwinTools, cctools, libtool, discount, exiv2, libmaxminddb
+, CoreServices, DarwinTools, cctools, libtool, discount, exiv2, libmaxminddb, libyaml
 }@args:
 
 let
@@ -544,6 +544,10 @@ in
     ];
   };
 
+  psych = attrs: {
+    buildInputs = [ libyaml ];
+  };
+
   puma = attrs: {
     buildInputs = [ openssl ];
   };