diff --git a/drivers/clk/versatile/clk-icst.c b/drivers/clk/versatile/clk-icst.c
index e62f8cb2c9b5..3bca438ecd19 100644
--- a/drivers/clk/versatile/clk-icst.c
+++ b/drivers/clk/versatile/clk-icst.c
@@ -78,6 +78,9 @@ static int vco_set(struct clk_icst *icst, struct icst_vco vco)
 	ret = regmap_read(icst->map, icst->vcoreg_off, &val);
 	if (ret)
 		return ret;
+
+	/* Mask the 18 bits used by the VCO */
+	val &= ~0x7ffff;
 	val |= vco.v | (vco.r << 9) | (vco.s << 16);
 
 	/* This magic unlocks the VCO so it can be controlled */