diff --git a/ports/esp32/machine_timer.c b/ports/esp32/machine_timer.c
index 5e249e46e6..0dbedad883 100644
--- a/ports/esp32/machine_timer.c
+++ b/ports/esp32/machine_timer.c
@@ -157,7 +157,7 @@ static void machine_timer_enable(machine_timer_obj_t *self) {
     // Initialise the timer.
     timer_hal_init(&self->hal_context, self->group, self->index);
     timer_ll_enable_counter(self->hal_context.dev, self->index, false);
-    timer_ll_set_clock_source(self->hal_context.dev, self->index, GPTIMER_CLK_SRC_APB);
+    timer_ll_set_clock_source(self->hal_context.dev, self->index, GPTIMER_CLK_SRC_DEFAULT);
     timer_ll_set_clock_prescale(self->hal_context.dev, self->index, TIMER_DIVIDER);
     timer_hal_set_counter_value(&self->hal_context, 0);
     timer_ll_set_count_direction(self->hal_context.dev, self->index, GPTIMER_COUNT_UP);