diff --git a/boot/boot_serial/src/boot_serial.c b/boot/boot_serial/src/boot_serial.c
index 4ebff17..468fa6a 100644
--- a/boot/boot_serial/src/boot_serial.c
+++ b/boot/boot_serial/src/boot_serial.c
@@ -849,7 +849,9 @@
 
     off = 0;
     while (timeout_in_ms > 0 || bs_entry) {
+#ifndef MCUBOOT_SERIAL_WAIT_FOR_DFU
         MCUBOOT_CPU_IDLE();
+#endif
         MCUBOOT_WATCHDOG_FEED();
 #ifdef MCUBOOT_SERIAL_WAIT_FOR_DFU
         uint32_t start = k_uptime_get_32();