-#define M25_SELECT(cs) ao_spi_get_mask(AO_M25_SPI_CS_PORT,cs,AO_M25_SPI_BUS, AO_SPI_SPEED_FAST)
+#define AO_M25_SPI_SPEED ao_spi_speed(AO_M25_SPI_BUS, 10000000) /* this seems like a reasonable minimum speed to require */
+
+#define M25_SELECT(cs) ao_spi_get_mask(AO_M25_SPI_CS_PORT,cs,AO_M25_SPI_BUS,AO_M25_SPI_SPEED)