diff --git a/cpu/sam0_common/periph/rtc.c b/cpu/sam0_common/periph/rtc.c
index 7ab2a7a35f..d5d39594c1 100644
--- a/cpu/sam0_common/periph/rtc.c
+++ b/cpu/sam0_common/periph/rtc.c
@@ -65,10 +65,8 @@ static inline void _rtc_set_enabled(bool on)
 #ifdef CPU_SAMD21
 static void _rtc_clock_setup(void)
 {
-    /* Setup clock GCLK2 with OSC32K divided by 32 */
-    GCLK->GENDIV.reg = GCLK_GENDIV_ID(2) | GCLK_GENDIV_DIV(4);
-    GCLK->GENCTRL.bit.DIVSEL = 1;
-    GCLK->CLKCTRL.reg = GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN(2) | GCLK_CLKCTRL_ID_RTC;
+    /* Use 1024 Hz GCLK4 */
+    GCLK->CLKCTRL.reg = GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN(4) | GCLK_CLKCTRL_ID_RTC;
     while (GCLK->STATUS.bit.SYNCBUSY) {}
 }
 #else