diff --git a/pkgs/development/ruby-modules/gem-config/default.nix b/pkgs/development/ruby-modules/gem-config/default.nix
index f9f1addd4c31..41fcc336c135 100644
--- a/pkgs/development/ruby-modules/gem-config/default.nix
+++ b/pkgs/development/ruby-modules/gem-config/default.nix
@@ -406,7 +406,7 @@ in
 
   rugged = attrs: {
     nativeBuildInputs = [ pkgconfig ];
-    buildInputs = [ cmake openssl libssh2 zlib ];
+    buildInputs = [ which cmake openssl libssh2 zlib ];
     dontUseCmakeConfigure = true;
   };