diff --git a/drivers/ide/pci/serverworks.c b/drivers/ide/pci/serverworks.c
index 1f80c6d58805b1fb2d2f5fad997689d10264c332..47bcd91c9b5f50e5434667ee32db50afaddd76e5 100644
--- a/drivers/ide/pci/serverworks.c
+++ b/drivers/ide/pci/serverworks.c
@@ -179,7 +179,7 @@ static int svwks_tune_chipset (ide_drive_t *drive, u8 xferspeed)
 				   ((dma_stat&(1<<(5+unit)))==(1<<(5+unit)))) {
 				u8 dmaspeed = dma_timing;
 
-				dma_timing &= ~0xFF;
+				dma_timing &= ~0xFFU;
 				if ((dmaspeed & 0x20) == 0x20)
 					dmaspeed = XFER_MW_DMA_2;
 				else if ((dmaspeed & 0x21) == 0x21)
@@ -193,7 +193,7 @@ static int svwks_tune_chipset (ide_drive_t *drive, u8 xferspeed)
 			} else if (pio_timing) {
 				u8 piospeed = pio_timing;
 
-				pio_timing &= ~0xFF;
+				pio_timing &= ~0xFFU;
 				if ((piospeed & 0x20) == 0x20)
 					piospeed = XFER_PIO_4;
 				else if ((piospeed & 0x22) == 0x22)
@@ -214,8 +214,8 @@ static int svwks_tune_chipset (ide_drive_t *drive, u8 xferspeed)
 
 oem_setup_failed:
 
-	pio_timing	&= ~0xFF;
-	dma_timing	&= ~0xFF;
+	pio_timing	&= ~0xFFU;
+	dma_timing	&= ~0xFFU;
 	ultra_timing	&= ~(0x0F << (4*unit));
 	ultra_enable	&= ~(0x01 << drive->dn);
 	csb5_pio	&= ~(0x0F << (4*drive->dn));