diff --git a/CMakeLists.txt b/CMakeLists.txt
index 553883d..4e68e48 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -49,6 +49,12 @@ set_property(CACHE TCB_CLKSEL PROPERTY STRINGS
     TCB_CLKSEL_CLKTCA_gc
 )
 
+set(USART_RXMODE "USART_RXMODE_CLK2X_gc" CACHE STRING "USART at normal or double speed operation")
+set_property(CACHE USART_RXMODE PROPERTY STRINGS
+    USART_RXMODE_CLK2X_gc
+    USART_RXMODE_NORMAL_gc
+)
+
 if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
   if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "8.3")
     message(FATAL_ERROR "Insufficient AVR-GCC version; Support for ATtiny3216 was added in GCC v8")
@@ -120,6 +126,7 @@ target_compile_definitions(mockingboard PRIVATE
     CLK_PRESCALE_DIV=${CLK_PRESCALE_DIV}
     __CLK_PRESCALE_DIV=__${CLK_PRESCALE_DIV}
     TCB_CLKSEL=${TCB_CLKSEL}
+    USART_RXMODE=${USART_RXMODE}
 )
 target_compile_options(mockingboard PRIVATE
     --param=min-pagesize=0
diff --git a/CMakePresets.json b/CMakePresets.json
index 2ce4148..f5a4a17 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -23,7 +23,8 @@
             "cacheVariables": {
                 "CMAKE_BUILD_TYPE": "RelWithDebInfo",
                 "FREQSEL": "20MHz",
-                "TCB_CLKSEL": "TCB_CLKSEL_CLKDIV1_gc"
+                "TCB_CLKSEL": "TCB_CLKSEL_CLKDIV1_gc",
+                "USART_RXMODE": "USART_RXMODE_CLK2X_gc"
             }
         }
     ]
diff --git a/src/com232.c b/src/com232.c
index ef5b8dd..1ce9992 100644
--- a/src/com232.c
+++ b/src/com232.c
@@ -20,9 +20,6 @@
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
-#define USART_BAUD_RATE(BAUD_RATE)                                             \
-  (uint16_t)((float)(F_CPU * 64 / (16 * (float)BAUD_RATE)) + 0.5)
-
 #include <avr/interrupt.h>
 #include <avr/io.h>
 #include <avr/sfr_defs.h>
@@ -31,6 +28,15 @@
 #include "com232.h"
 #include "timing.h"
 
+#if USART_RXMODE == USART_RXMODE_CLK2X_gc
+#define RXMODE_S 9
+#elif USART_RXMODE == USART_RXMODE_NORMAL_gc
+#define RXMODE_S 16
+#endif
+
+#define USART_BAUD_RATE(BAUD_RATE)                                             \
+  (uint16_t)((float)(F_CPU * 64 / (USART_RXMODE * (float)BAUD_RATE)) + 0.5)
+
 uint8_t RS232_RxCharBuffer[25], RS232_RxCharBegin, RS232_RxCharEnd;
 uint8_t readkey;
 
@@ -44,11 +50,11 @@ void RS232_Init(void) {
 
   USART0.CTRLA = USART_RXCIE_bm;                 // Enable receive interrupts
   USART0.CTRLB = USART_RXEN_bm | USART_TXEN_bm | // Enable Rx/Tx and set receive
-                 USART_RXMODE_NORMAL_gc;         //  mode normal
+                 USART_RXMODE;                   //  mode
   USART0.CTRLC = USART_CMODE_ASYNCHRONOUS_gc | USART_PMODE_DISABLED_gc |
                  USART_CHSIZE_8BIT_gc |
                  USART_SBMODE_1BIT_gc; // Async UART with 8N1 config
-  USART0.BAUD = USART_BAUD_RATE(250000);
+  USART0.BAUD = USART_BAUD_RATE(500000);
 }
 
 ISR(USART0_RXC_vect) {