diff --git a/boards/nucleo-l031k6/include/periph_conf.h b/boards/nucleo-l031k6/include/periph_conf.h
index 6fcabe74f7..58f0eebfa6 100644
--- a/boards/nucleo-l031k6/include/periph_conf.h
+++ b/boards/nucleo-l031k6/include/periph_conf.h
@@ -36,6 +36,7 @@ extern "C" {
  */
 #define CLOCK_HSI           (16000000U)         /* internal oscillator */
 #define CLOCK_CORECLOCK     (32000000U)         /* desired core clock frequency */
+#define CLOCK_LSE           (1)                 /* enable low speed external oscillator */
 
 /* configuration of PLL prescaler and multiply values */
 /* CORECLOCK := HSI / CLOCK_PLL_DIV * CLOCK_PLL_MUL */
diff --git a/boards/nucleo-l053r8/include/periph_conf.h b/boards/nucleo-l053r8/include/periph_conf.h
index 4e4b0b23c3..bf52cda2e2 100644
--- a/boards/nucleo-l053r8/include/periph_conf.h
+++ b/boards/nucleo-l053r8/include/periph_conf.h
@@ -36,6 +36,7 @@ extern "C" {
  */
 #define CLOCK_HSI           (16000000U)         /* internal oscillator */
 #define CLOCK_CORECLOCK     (32000000U)         /* desired core clock frequency */
+#define CLOCK_LSE           (1)                 /* enable low speed external oscillator */
 
 /* configuration of PLL prescaler and multiply values */
 /* CORECLOCK := HSI / CLOCK_PLL_DIV * CLOCK_PLL_MUL */