diff --git a/STM32F1/libraries/SPI/src/SPI.cpp b/STM32F1/libraries/SPI/src/SPI.cpp
index c07e2ea..4d8787d 100644
--- a/STM32F1/libraries/SPI/src/SPI.cpp
+++ b/STM32F1/libraries/SPI/src/SPI.cpp
@@ -161,7 +161,7 @@ void SPIClass::begin(void) {
 void SPIClass::beginSlave(void) {
     spi_init(_currentSetting->spi_d);
     configure_gpios(_currentSetting->spi_d, 0);
-    uint32 flags = ((_currentSetting->bitOrder == MSBFIRST ? SPI_FRAME_MSB : SPI_FRAME_LSB) | _currentSetting->dataSize | SPI_RX_ONLY);
+    uint32 flags = ((_currentSetting->bitOrder == MSBFIRST ? SPI_FRAME_MSB : SPI_FRAME_LSB) | _currentSetting->dataSize);
     spi_slave_enable(_currentSetting->spi_d, (spi_mode)_currentSetting->dataMode, flags);
     // added for DMA callbacks.
     _currentSetting->state = SPI_STATE_READY;