diff --git a/pkgs/servers/sql/postgresql/ext/pgroonga.nix b/pkgs/servers/sql/postgresql/ext/pgroonga.nix
index 78dd305c98d6..bb0f33490b7e 100644
--- a/pkgs/servers/sql/postgresql/ext/pgroonga.nix
+++ b/pkgs/servers/sql/postgresql/ext/pgroonga.nix
@@ -10,17 +10,7 @@ stdenv.mkDerivation rec {
   };
 
   nativeBuildInputs = [ pkg-config ];
-  buildInputs =
-    let
-      groonga-with-msgpack = groonga.overrideAttrs (oa: {
-        buildInputs = oa.buildInputs ++ [ msgpack-c ];
-      });
-    in
-    [
-      postgresql
-      msgpack-c
-      groonga-with-msgpack
-    ];
+  buildInputs = [ postgresql msgpack-c groonga ];
 
   makeFlags = [
     "HAVE_MSGPACK=1"