diff --git a/arch/i386/kernel/hpet.c b/arch/i386/kernel/hpet.c
index 23e7d2c5d25315eefae9b1bbbe3aafd0a2c279d4..c6737c35815db8fff2ede01f0322773eda864a34 100644
--- a/arch/i386/kernel/hpet.c
+++ b/arch/i386/kernel/hpet.c
@@ -6,7 +6,7 @@
 #include <asm/hpet.h>
 #include <asm/io.h>
 
-#define HPET_MASK	0xFFFFFFFF
+#define HPET_MASK	CLOCKSOURCE_MASK(32)
 #define HPET_SHIFT	22
 
 /* FSEC = 10^-15 NSEC = 10^-9 */
@@ -23,7 +23,7 @@ static struct clocksource clocksource_hpet = {
 	.name		= "hpet",
 	.rating		= 250,
 	.read		= read_hpet,
-	.mask		= (cycle_t)HPET_MASK,
+	.mask		= HPET_MASK,
 	.mult		= 0, /* set below */
 	.shift		= HPET_SHIFT,
 	.is_continuous	= 1,
diff --git a/arch/i386/kernel/i8253.c b/arch/i386/kernel/i8253.c
index 5b13739a7ff49e79e2e9f3cb840a862e84a0353a..38aa7f19f1d30ef006377a0b80cc3cd6f15209a0 100644
--- a/arch/i386/kernel/i8253.c
+++ b/arch/i386/kernel/i8253.c
@@ -69,7 +69,7 @@ static struct clocksource clocksource_pit = {
 	.name	= "pit",
 	.rating = 110,
 	.read	= pit_read,
-	.mask	= (cycle_t)-1,
+	.mask	= CLOCKSOURCE_MASK(64),
 	.mult	= 0,
 	.shift	= 20,
 };
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index 1c3c927755de996447266cc4eaea4004c4b8ff77..7e0d8dab207519f7625b722327ce06e531f077c5 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -337,7 +337,7 @@ static struct clocksource clocksource_tsc = {
 	.name			= "tsc",
 	.rating			= 300,
 	.read			= read_tsc,
-	.mask			= (cycle_t)-1,
+	.mask			= CLOCKSOURCE_MASK(64),
 	.mult			= 0, /* to be set */
 	.shift			= 22,
 	.update_callback	= tsc_update_callback,
diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c
index 066dc77433d5e25991f31df84de3a126edaffd3e..7ad3be8c0f49e4f0bfc1722418ba377e9712de74 100644
--- a/drivers/clocksource/acpi_pm.c
+++ b/drivers/clocksource/acpi_pm.c
@@ -32,7 +32,7 @@
  */
 u32 pmtmr_ioport __read_mostly;
 
-#define ACPI_PM_MASK 0xFFFFFF /* limit it to 24 bits */
+#define ACPI_PM_MASK CLOCKSOURCE_MASK(24) /* limit it to 24 bits */
 
 static inline u32 read_pmtmr(void)
 {
diff --git a/drivers/clocksource/cyclone.c b/drivers/clocksource/cyclone.c
index 5906a0af825dcffe7c7c3f45b4e7bfd5cba3b506..bf4d3d50d1c4e9a7c76c05f9b8476ebf3896f8c2 100644
--- a/drivers/clocksource/cyclone.c
+++ b/drivers/clocksource/cyclone.c
@@ -14,7 +14,7 @@
 #define CYCLONE_MPCS_OFFSET	0x51A8		/* offset to select register */
 #define CYCLONE_MPMC_OFFSET	0x51D0		/* offset to count register */
 #define CYCLONE_TIMER_FREQ	99780000	/* 100Mhz, but not really */
-#define CYCLONE_TIMER_MASK	0xFFFFFFFF	/* 32 bit mask */
+#define CYCLONE_TIMER_MASK	CLOCKSOURCE_MASK(32) /* 32 bit mask */
 
 int use_cyclone = 0;
 static void __iomem *cyclone_ptr;
@@ -28,7 +28,7 @@ static struct clocksource clocksource_cyclone = {
 	.name		= "cyclone",
 	.rating		= 250,
 	.read		= read_cyclone,
-	.mask		= (cycle_t)CYCLONE_TIMER_MASK,
+	.mask		= CYCLONE_TIMER_MASK,
 	.mult		= 10,
 	.shift		= 0,
 	.is_continuous	= 1,
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 5f4a7f72f3ee4adc4729dfdedd71f227091d70a0..4bc94282c364ff7ef5e89aef3817cbe12bba6e95 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -65,6 +65,8 @@ struct clocksource {
 	u64 interval_snsecs;
 };
 
+/* simplify initialization of mask field */
+#define CLOCKSOURCE_MASK(bits) (cycle_t)(bits<64 ? ((1ULL<<bits)-1) : -1)
 
 /**
  * clocksource_khz2mult - calculates mult from khz and shift