diff --git a/rtsx.c b/rtsx.c
index 8082c25..3bfb6b3 100644
--- a/rtsx.c
+++ b/rtsx.c
@@ -837,7 +837,7 @@ rtsx_set_sd_clock(struct rtsx_softc *sc, uint32_t freq)
 		n = 80; /* minimum */
 		div = RTSX_CLK_DIV_8;
 		mcu = 7;
-		RTSX_SET(sc, RTSX_SD_CFG1, RTSX_CLK_DIVIDE_128);
+		RTSX_CLR(sc, RTSX_SD_CFG1, RTSX_CLK_DIVIDE_MASK);
 		break;
 	case RTSX_SDCLK_25MHZ:
 		n = 100;