diff --git a/src/tests/meta-kms-test-utils.c b/src/tests/meta-kms-test-utils.c
index 671719f62..468ca3a7f 100644
--- a/src/tests/meta-kms-test-utils.c
+++ b/src/tests/meta-kms-test-utils.c
@@ -30,6 +30,8 @@
 #include "backends/native/meta-kms-connector.h"
 #include "backends/native/meta-kms-crtc.h"
 #include "backends/native/meta-kms-device.h"
+#include "backends/native/meta-kms-mode.h"
+#include "backends/native/meta-kms-update.h"
 #include "backends/native/meta-kms.h"
 
 MetaKmsDevice *
@@ -103,3 +105,28 @@ meta_create_test_dumb_buffer (MetaKmsDevice *device,
 
   return META_DRM_BUFFER (dumb_buffer);
 }
+
+MetaDrmBuffer *
+meta_create_test_mode_dumb_buffer (MetaKmsDevice *device,
+                                   MetaKmsMode   *mode)
+{
+  return meta_create_test_dumb_buffer (device,
+                                       meta_kms_mode_get_width (mode),
+                                       meta_kms_mode_get_height (mode));
+}
+
+MetaFixed16Rectangle
+meta_get_mode_fixed_rect_16 (MetaKmsMode *mode)
+{
+  return META_FIXED_16_RECTANGLE_INIT_INT (0, 0,
+                                           meta_kms_mode_get_width (mode),
+                                           meta_kms_mode_get_height (mode));
+}
+
+MetaRectangle
+meta_get_mode_rect (MetaKmsMode *mode)
+{
+  return META_RECTANGLE_INIT (0, 0,
+                              meta_kms_mode_get_width (mode),
+                              meta_kms_mode_get_height (mode));
+}
diff --git a/src/tests/meta-kms-test-utils.h b/src/tests/meta-kms-test-utils.h
index 77b6ad827..e28a1425f 100644
--- a/src/tests/meta-kms-test-utils.h
+++ b/src/tests/meta-kms-test-utils.h
@@ -24,6 +24,7 @@
 #include "backends/native/meta-drm-buffer.h"
 #include "backends/native/meta-kms-types.h"
 #include "meta/meta-context.h"
+#include "meta/boxes.h"
 
 MetaKmsDevice * meta_get_test_kms_device (MetaContext *context);
 
@@ -35,4 +36,11 @@ MetaDrmBuffer * meta_create_test_dumb_buffer (MetaKmsDevice *device,
                                               int            width,
                                               int            height);
 
+MetaDrmBuffer * meta_create_test_mode_dumb_buffer (MetaKmsDevice *device,
+                                                   MetaKmsMode   *mode);
+
+MetaFixed16Rectangle meta_get_mode_fixed_rect_16 (MetaKmsMode *mode);
+
+MetaRectangle meta_get_mode_rect (MetaKmsMode *mode);
+
 #endif /* META_KMS_TEST_UTILS_H */
diff --git a/src/tests/native-kms-updates.c b/src/tests/native-kms-updates.c
index 882f61de5..ff983f004 100644
--- a/src/tests/native-kms-updates.c
+++ b/src/tests/native-kms-updates.c
@@ -106,19 +106,15 @@ meta_test_kms_update_plane_assignments (void)
 
   mode_width = meta_kms_mode_get_width (mode);
   mode_height = meta_kms_mode_get_height (mode);
-  primary_buffer = meta_create_test_dumb_buffer (device,
-                                                 mode_width, mode_height);
+  primary_buffer = meta_create_test_mode_dumb_buffer (device, mode);
 
   primary_plane_assignment =
     meta_kms_update_assign_plane (update,
                                   crtc,
                                   primary_plane,
                                   primary_buffer,
-                                  META_FIXED_16_RECTANGLE_INIT_INT (0, 0,
-                                                                    mode_width,
-                                                                    mode_height),
-                                  META_RECTANGLE_INIT (0, 0,
-                                                       mode_width, mode_height),
+                                  meta_get_mode_fixed_rect_16 (mode),
+                                  meta_get_mode_rect (mode),
                                   META_KMS_ASSIGN_PLANE_FLAG_NONE);
   g_assert_nonnull (primary_plane_assignment);
   g_assert_cmpint (primary_plane_assignment->src_rect.x, ==, 0);