diff --git a/tests/interactive/test-cogl-vertex-buffer.c b/tests/interactive/test-cogl-vertex-buffer.c
index a420b7871..8d134475d 100644
--- a/tests/interactive/test-cogl-vertex-buffer.c
+++ b/tests/interactive/test-cogl-vertex-buffer.c
@@ -147,7 +147,7 @@ on_paint (ClutterActor *actor, TestState *state)
                                     state->indices,
                                     0, /* min index */
                                     (MESH_WIDTH + 1) *
-                                    (MESH_HEIGHT + 1), /* max index */
+                                    (MESH_HEIGHT + 1) - 1, /* max index */
                                     0, /* indices offset */
                                     state->n_static_indices);
 }