diff --git a/Firmware/Src/syscalls.c b/Firmware/Src/syscalls.c
index 5c92c709..ee9da08f 100644
--- a/Firmware/Src/syscalls.c
+++ b/Firmware/Src/syscalls.c
@@ -26,25 +26,24 @@ int _write(int file, char* data, int len) {
     int written = 0;
     switch (serial_printf_select) {
         case SERIAL_PRINTF_IS_USB: {
-            // transmit over CDC
-            uint8_t status = CDC_Transmit_FS((uint8_t*)data, len);
-            written = (status == USBD_OK) ? len : 0;
-
-            // Wait for transmission to complete
-            osSemaphoreWait(sem_usb_tx, osWaitForever);
+            // Wait for the interface to be available
+            osStatus sem_stat = osSemaphoreWait(sem_usb_tx, osWaitForever);
+            if (sem_stat == osOK) {
+                uint8_t status = CDC_Transmit_FS((uint8_t*)data, len);  // transmit over CDC
+                written = (status == USBD_OK) ? len : 0;
+            }
         } break;
 
         case SERIAL_PRINTF_IS_UART: {
             //Check length
             if (len > UART_TX_BUFFER_SIZE)
                 return 0;
-            // memcpy data into uart_tx_buf
-            memcpy(uart_tx_buf, data, len);
-            // Start DMA background trasnfer
-            HAL_UART_Transmit_DMA(&huart4, uart_tx_buf, len);
-            
-            // Wait for the transmission to complete
-            osSemaphoreWait(sem_uart_dma, osWaitForever);
+            // Wait for the interface to be available
+            osStatus sem_stat = osSemaphoreWait(sem_uart_dma, osWaitForever);
+            if (sem_stat == osOK) {
+                memcpy(uart_tx_buf, data, len);                    // memcpy data into uart_tx_buf
+                HAL_UART_Transmit_DMA(&huart4, uart_tx_buf, len);  // Start DMA background transfer
+            }
         } break;
 
         default: {