diff --git a/cores/arduino/UART.cpp b/cores/arduino/UART.cpp
index 8e0520bc..c6065825 100644
--- a/cores/arduino/UART.cpp
+++ b/cores/arduino/UART.cpp
@@ -140,7 +140,7 @@ void UartClass::begin(unsigned long baud, uint16_t config)
     uint8_t oldSREG = SREG;
     cli();
 
-    baud_setting = (((8 * F_CPU_CORRECTED) / baud) + 1) / 2;
+    baud_setting = (((8 * F_CPU) / baud) + 1) / 2;
     // Disable CLK2X
     (*_hwserial_module).CTRLB &= (~USART_RXMODE_CLK2X_gc);
     (*_hwserial_module).CTRLB |= USART_RXMODE_NORMAL_gc;
@@ -148,8 +148,7 @@ void UartClass::begin(unsigned long baud, uint16_t config)
     _written = false;
 
     int8_t sigrow_val = SIGROW.OSC16ERR5V;
-    baud_setting *= (1024 + sigrow_val);
-    baud_setting /= (1024 - abs(sigrow_val));
+    baud_setting += (baud_setting * sigrow_val) / 1024;
 
     // assign the baud_setting, a.k.a. BAUD (USART Baud Rate Register)
     (*_hwserial_module).BAUD = (int16_t) baud_setting;