diff --git a/lib/stm32/f1/rtc.c b/lib/stm32/f1/rtc.c
index 08a49536..cfc5f5b6 100644
--- a/lib/stm32/f1/rtc.c
+++ b/lib/stm32/f1/rtc.c
@@ -67,6 +67,8 @@ void rtc_awake_from_off(osc_t clock_source)
 		RCC_BDCR |= (1 << 9) | (1 << 8);
 		break;
 	case PLL:
+	case PLL2:
+	case PLL3:
 	case HSI:
 		/* Unusable clock source, here to prevent warnings. */
 		/* Turn off clock sources to RTC. */