diff --git a/cpu/samd21/include/periph_cpu.h b/cpu/samd21/include/periph_cpu.h
index 608ba468be..69b8e8272f 100644
--- a/cpu/samd21/include/periph_cpu.h
+++ b/cpu/samd21/include/periph_cpu.h
@@ -32,7 +32,7 @@ extern "C" {
  * @brief   Override the default initial PM blocker
  * @todo   Idle modes are enabled by default, deep sleep mode blocked
  */
-#define PM_BLOCKER_INITIAL  { .val_u32 = 0x00000001 }
+#define PM_BLOCKER_INITIAL      0x00000001
 
 /**
  * @name   SAMD21 sleep modes for PM
diff --git a/cpu/saml1x/include/periph_cpu.h b/cpu/saml1x/include/periph_cpu.h
index 1732b3ff6b..93eb7bb9b5 100644
--- a/cpu/saml1x/include/periph_cpu.h
+++ b/cpu/saml1x/include/periph_cpu.h
@@ -30,7 +30,7 @@ extern "C" {
  * @brief   Override the default initial PM blocker
  * @todo   Idle modes are enabled by default, deep sleep mode blocked
  */
-#define PM_BLOCKER_INITIAL  { .val_u32 = 0x00000001 }
+#define PM_BLOCKER_INITIAL  0x00000001
 
 /**
  * @name   SAML1x GCLK definitions
diff --git a/sys/pm_layered/pm.c b/sys/pm_layered/pm.c
index ede2b51dd7..3f63bfa7b9 100644
--- a/sys/pm_layered/pm.c
+++ b/sys/pm_layered/pm.c
@@ -30,7 +30,7 @@
 #endif
 
 #ifndef PM_BLOCKER_INITIAL
-#define PM_BLOCKER_INITIAL { .val_u32 = 0x01010101 }
+#define PM_BLOCKER_INITIAL 0x01010101   /* block all by default */
 #endif
 
 /**
@@ -44,7 +44,7 @@ typedef union {
 /**
  * @brief Global variable for keeping track of blocked modes
  */
-volatile pm_blocker_t pm_blocker = PM_BLOCKER_INITIAL;
+volatile pm_blocker_t pm_blocker = { .val_u32 = PM_BLOCKER_INITIAL };
 
 void pm_set_lowest(void)
 {