diff --git a/pyanaconda/modules/payloads/payload/rpm_ostree/installation.py b/pyanaconda/modules/payloads/payload/rpm_ostree/installation.py
index 083f1187db9..6f1e77e50d0 100644
--- a/pyanaconda/modules/payloads/payload/rpm_ostree/installation.py
+++ b/pyanaconda/modules/payloads/payload/rpm_ostree/installation.py
@@ -572,7 +572,7 @@ def _set_kargs(self):
             device_tree.GetDeviceData(root_id)
         )
 
-        set_kargs_args = ["admin", "instutil", "set-kargs"]
+        set_kargs_args = ["admin", "instutil", "set-kargs", "--merge"]
         set_kargs_args.extend(bootloader.GetArguments())
         set_kargs_args.append("root=" + device_tree.GetFstabSpec(root_id))
         set_kargs_args.append("vconsole.keymap=" + localization.VirtualConsoleKeymap)
diff --git a/tests/unit_tests/pyanaconda_tests/modules/payloads/payload/test_rpm_ostree_tasks.py b/tests/unit_tests/pyanaconda_tests/modules/payloads/payload/test_rpm_ostree_tasks.py
index 81727583a5d..03ea494ab25 100644
--- a/tests/unit_tests/pyanaconda_tests/modules/payloads/payload/test_rpm_ostree_tasks.py
+++ b/tests/unit_tests/pyanaconda_tests/modules/payloads/payload/test_rpm_ostree_tasks.py
@@ -724,6 +724,7 @@ def test_btrfs_run(self, devdata_mock, storage_mock, localization_mock,
                 ["admin",
                  "instutil",
                  "set-kargs",
+                 "--merge",
                  "BOOTLOADER-ARGS",
                  "root=FSTAB-SPEC",
                  "vconsole.keymap=cs",
@@ -773,6 +774,7 @@ def test_nonbtrfs_run(self, devdata_mock, storage_mock, localization_mock,
                 ["admin",
                  "instutil",
                  "set-kargs",
+                 "--merge",
                  "BOOTLOADER-ARGS",
                  "root=FSTAB-SPEC",
                  "vconsole.keymap=cs",
@@ -825,6 +827,7 @@ def test_bootupd_run(self, devdata_mock, storage_mock, localization_mock, symlin
                     ["admin",
                      "instutil",
                      "set-kargs",
+                     "--merge",
                      "BOOTLOADER-ARGS",
                      "root=FSTAB-SPEC",
                      "vconsole.keymap=cs",
@@ -878,6 +881,7 @@ def test_bootupd_run_with_leavebootorder(self, devdata_mock, storage_mock, local
                     ["admin",
                      "instutil",
                      "set-kargs",
+                     "--merge",
                      "BOOTLOADER-ARGS",
                      "root=FSTAB-SPEC",
                      "vconsole.keymap=cs",