diff --git a/src/stm32/stm32f0.c b/src/stm32/stm32f0.c
index a6d5e069..3b4d35d4 100644
--- a/src/stm32/stm32f0.c
+++ b/src/stm32/stm32f0.c
@@ -211,7 +211,8 @@ armcm_main(void)
     FLASH->ACR = (1 << FLASH_ACR_LATENCY_Pos) | FLASH_ACR_PRFTBE;
 
     // Configure main clock
-    if (CONFIG_MACH_STM32F042 && CONFIG_STM32_CLOCK_REF_INTERNAL)
+    if (CONFIG_MACH_STM32F042 && CONFIG_STM32_CLOCK_REF_INTERNAL
+        && CONFIG_USBSERIAL)
         hsi48_setup();
     else
         pll_setup();