diff --git a/megaavr/cores/megatinycore/UART0.cpp b/megaavr/cores/megatinycore/UART0.cpp
index 7befd6cf..623beea3 100644
--- a/megaavr/cores/megatinycore/UART0.cpp
+++ b/megaavr/cores/megatinycore/UART0.cpp
@@ -105,7 +105,7 @@
   #endif
   #if !(defined(USE_ASM_DRE) && USE_ASM_DRE == 1 && \
        (SERIAL_RX_BUFFER_SIZE == 256 || SERIAL_RX_BUFFER_SIZE == 128 || SERIAL_RX_BUFFER_SIZE == 64 || SERIAL_RX_BUFFER_SIZE == 32 || SERIAL_RX_BUFFER_SIZE == 16) && \
-       (SERIAL_RX_BUFFER_SIZE == 256 || SERIAL_TX_BUFFER_SIZE == 128 || SERIAL_TX_BUFFER_SIZE == 64 || SERIAL_TX_BUFFER_SIZE == 32 || SERIAL_TX_BUFFER_SIZE == 16))
+       (SERIAL_TX_BUFFER_SIZE == 256 || SERIAL_TX_BUFFER_SIZE == 128 || SERIAL_TX_BUFFER_SIZE == 64 || SERIAL_TX_BUFFER_SIZE == 32 || SERIAL_TX_BUFFER_SIZE == 16))
     ISR(USART0_DRE_vect) {
       HardwareSerial::_tx_data_empty_irq(Serial);
     }