diff --git a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/objects.h b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/objects.h
index 35daa56017..338b68c428 100644
--- a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/objects.h
+++ b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/objects.h
@@ -129,6 +129,7 @@ struct serial_s {
     DMA_OPTIONS_t dmaOptionsTX;
     DMA_OPTIONS_t dmaOptionsRX;
 #endif
+    uint32_t sleep_blocked;
 };
 #endif