diff --git a/Cargo.lock b/Cargo.lock
index a996982b..4bea80bc 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -676,6 +676,7 @@ dependencies = [
  "cmake",
  "cxx",
  "cxx-build",
+ "glib",
  "system-deps 3.0.0",
 ]
 
@@ -1236,6 +1237,7 @@ dependencies = [
  "gio-sys",
  "glib",
  "glib-sys",
+ "gobject-sys",
  "indicatif",
  "lazy_static",
  "libc",
diff --git a/Cargo.toml b/Cargo.toml
index 9a0452de..1920d166 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -34,6 +34,7 @@ cxx = "1.0.32"
 envsubst = "0.2.0"
 gio = "0.9.1"
 gio-sys = "0.10.1"
+gobject-sys = "0.10.0"
 glib = "0.10.3"
 glib-sys = "0.10.1"
 indicatif = "0.15.0"
diff --git a/rust/libdnf-sys/Cargo.toml b/rust/libdnf-sys/Cargo.toml
index d011c67d..48566c17 100644
--- a/rust/libdnf-sys/Cargo.toml
+++ b/rust/libdnf-sys/Cargo.toml
@@ -7,6 +7,7 @@ links = "dnf"
 
 [dependencies]
 cxx = "1.0.32"
+glib = "0.10.3"
 
 [lib]
 name = "libdnf_sys"
diff --git a/rust/src/cxxrsutil.rs b/rust/src/cxxrsutil.rs
index e81ba27e..dcee49d2 100644
--- a/rust/src/cxxrsutil.rs
+++ b/rust/src/cxxrsutil.rs
@@ -80,7 +80,7 @@ macro_rules! cxxrs_bind {
         paste! {
             $(
                 #[repr(transparent)]
-                pub struct [<FFI $ns $i>]($sys::[<$ns $i>]);
+                pub struct [<FFI $ns $i>](pub(crate) $sys::[<$ns $i>]);
 
                 unsafe impl ExternType for [<FFI $ns $i>] {
                     type Id = type_id!(rpmostreecxx::[<$ns $i>]);
@@ -96,6 +96,7 @@ macro_rules! cxxrs_bind {
 // This macro is special to ostree types currently.
 cxxrs_bind!(Ostree, ostree, ostree_sys, [Sysroot, Repo, Deployment]);
 cxxrs_bind!(G, gio, gio_sys, [Cancellable]);
+cxxrs_bind!(G, glib, gobject_sys, [Object]);
 cxxrs_bind!(G, glib, glib_sys, [VariantDict]);
 
 // An error type helper; separate from the GObject bridging
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index a117eef1..7c4255bf 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -35,6 +35,7 @@ pub mod ffi {
         #[allow(dead_code)]
         type OstreeRepo = crate::FFIOstreeRepo;
         type OstreeDeployment = crate::FFIOstreeDeployment;
+        type GObject = crate::FFIGObject;
         type GCancellable = crate::FFIGCancellable;
         type GVariantDict = crate::FFIGVariantDict;
 
@@ -258,8 +259,8 @@ pub mod ffi {
         fn ror_lockfile_read(filenames: &Vec<String>) -> Result<Vec<StringMapping>>;
         fn ror_lockfile_write(
             filename: &str,
-            packages: Vec<u64>,
-            rpmmd_repos: Vec<u64>,
+            packages: Pin<&mut CxxGObjectArray>,
+            rpmmd_repos: Pin<&mut CxxGObjectArray>,
         ) -> Result<()>;
     }
 
@@ -268,6 +269,13 @@ pub mod ffi {
         fn cache_branch_to_nevra(nevra: &str) -> String;
     }
 
+    unsafe extern "C++" {
+        include!("rpmostree-cxxrsutil.hpp");
+        type CxxGObjectArray;
+        fn length(self: Pin<&mut CxxGObjectArray>) -> u32;
+        fn get(self: Pin<&mut CxxGObjectArray>, i: u32) -> &mut GObject;
+    }
+
     unsafe extern "C++" {
         include!("rpmostree-util.h");
         // Currently only used in unit tests
diff --git a/rust/src/lockfile.rs b/rust/src/lockfile.rs
index c9f16ba0..ac4efa1c 100644
--- a/rust/src/lockfile.rs
+++ b/rust/src/lockfile.rs
@@ -21,6 +21,7 @@ use std::convert::TryInto;
 use std::io;
 use std::iter::Extend;
 use std::path::Path;
+use std::pin::Pin;
 
 /// Given a lockfile filename, parse it
 fn lockfile_parse<P: AsRef<Path>>(filename: P) -> Result<LockfileConfig> {
@@ -208,8 +209,8 @@ pub(crate) fn ror_lockfile_read(filenames: &Vec<String>) -> CxxResult<Vec<String
 
 pub(crate) fn ror_lockfile_write(
     filename: &str,
-    packages: Vec<u64>,
-    rpmmd_repos: Vec<u64>,
+    mut packages: Pin<&mut crate::ffi::CxxGObjectArray>,
+    mut rpmmd_repos: Pin<&mut crate::ffi::CxxGObjectArray>,
 ) -> CxxResult<()> {
     // get current time, but scrub nanoseconds; it's overkill to serialize that
     let now = {
@@ -225,8 +226,9 @@ pub(crate) fn ror_lockfile_write(
         }),
     };
 
-    for pkg in packages {
-        let pkg_ref = unsafe { &mut *(pkg as *mut libdnf_sys::DnfPackage) };
+    for i in 0..(packages.as_mut().length()) {
+        let pkg = packages.as_mut().get(i);
+        let pkg_ref = unsafe { &mut *(&mut pkg.0 as *mut _ as *mut libdnf_sys::DnfPackage) };
         let name = dnf_package_get_name(pkg_ref).unwrap();
         let evr = dnf_package_get_evr(pkg_ref).unwrap();
         let arch = dnf_package_get_arch(pkg_ref).unwrap();
@@ -250,8 +252,9 @@ pub(crate) fn ror_lockfile_write(
         .as_mut()
         .unwrap();
 
-    for rpmmd_repo in rpmmd_repos {
-        let repo_ref = unsafe { &mut *(rpmmd_repo as *mut libdnf_sys::DnfRepo) };
+    for i in 0..rpmmd_repos.as_mut().length() {
+        let repo_ref = rpmmd_repos.as_mut().get(i);
+        let repo_ref = unsafe { &mut *(&mut repo_ref.0 as *mut _ as *mut libdnf_sys::DnfRepo) };
         let id = dnf_repo_get_id(repo_ref).unwrap();
         let generated = dnf_repo_get_timestamp_generated(repo_ref).unwrap();
         let generated: i64 = match generated.try_into() {
diff --git a/src/app/rpmostree-compose-builtin-tree.cxx b/src/app/rpmostree-compose-builtin-tree.cxx
index 219f2689..37a99d6a 100644
--- a/src/app/rpmostree-compose-builtin-tree.cxx
+++ b/src/app/rpmostree-compose-builtin-tree.cxx
@@ -382,12 +382,8 @@ install_packages (RpmOstreeTreeComposeContext  *self,
       g_autoptr(GPtrArray) rpmmd_repos =
         rpmostree_get_enabled_rpmmd_repos (rpmostree_context_get_dnf (self->corectx),
                                            DNF_REPO_ENABLED_PACKAGES);
-      auto pkgs_v = rust::Vec<guint64>();
-      for (guint i = 0; i < pkgs->len; i++)
-        pkgs_v.push_back((guint64)pkgs->pdata[i]);
-      auto repos_v = rust::Vec<guint64>();
-      for (guint i = 0; i < rpmmd_repos->len; i++)
-        repos_v.push_back((guint64)rpmmd_repos->pdata[i]);
+      auto pkgs_v = rpmostreecxx::CxxGObjectArray(pkgs);
+      auto repos_v = rpmostreecxx::CxxGObjectArray(rpmmd_repos);
       rpmostreecxx::ror_lockfile_write(opt_write_lockfile_to, pkgs_v, repos_v);
     }
 
diff --git a/src/libpriv/rpmostree-cxxrs-prelude.h b/src/libpriv/rpmostree-cxxrs-prelude.h
index 8e0f6367..d20b6adc 100644
--- a/src/libpriv/rpmostree-cxxrs-prelude.h
+++ b/src/libpriv/rpmostree-cxxrs-prelude.h
@@ -29,6 +29,7 @@ namespace rpmostreecxx {
     typedef ::OstreeRepo OstreeRepo;
     typedef ::OstreeDeployment OstreeDeployment;
     typedef ::GCancellable GCancellable;
+    typedef ::GObject GObject;
     typedef ::GVariantDict GVariantDict;
 }
 
diff --git a/src/libpriv/rpmostree-cxxrsutil.hpp b/src/libpriv/rpmostree-cxxrsutil.hpp
new file mode 100644
index 00000000..9110343b
--- /dev/null
+++ b/src/libpriv/rpmostree-cxxrsutil.hpp
@@ -0,0 +1,53 @@
+/* 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2 of the licence or (at
+ * your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#pragma once
+
+#include <string>
+#include <exception>
+#include <sstream>
+#include <gio/gio.h>
+
+#include "rust/cxx.h"
+
+// Helpers corresponding to cxxrsutil.rs
+namespace rpmostreecxx {
+
+// Wrapper for an array of GObjects.  This is a hack until
+// cxx-rs gains support for either std::vector<> or Vec<T>
+// with nontrivial types.
+class CxxGObjectArray final {
+public:
+    CxxGObjectArray(GPtrArray *arr_p) : arr(arr_p) {
+        g_ptr_array_ref(arr);
+    };
+    ~CxxGObjectArray() {
+        g_ptr_array_unref(arr);
+    }
+
+    unsigned int length() {
+        return (unsigned int)arr->len;
+    }
+
+    ::GObject& get(unsigned int i) {
+        g_assert_cmpuint(i, <, arr->len);
+        return *(::GObject*)arr->pdata[i];
+    }
+    GPtrArray* arr;
+};
+
+} // namespace