diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
index c0e25125a55e..19a6b3f4d9cf 100644
--- a/drivers/clocksource/mmio.c
+++ b/drivers/clocksource/mmio.c
@@ -22,22 +22,22 @@ static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
 
 cycle_t clocksource_mmio_readl_up(struct clocksource *c)
 {
-	return readl_relaxed(to_mmio_clksrc(c)->reg);
+	return (cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg);
 }
 
 cycle_t clocksource_mmio_readl_down(struct clocksource *c)
 {
-	return ~readl_relaxed(to_mmio_clksrc(c)->reg);
+	return ~(cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg);
 }
 
 cycle_t clocksource_mmio_readw_up(struct clocksource *c)
 {
-	return readw_relaxed(to_mmio_clksrc(c)->reg);
+	return (cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg);
 }
 
 cycle_t clocksource_mmio_readw_down(struct clocksource *c)
 {
-	return ~(unsigned)readw_relaxed(to_mmio_clksrc(c)->reg);
+	return ~(cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg);
 }
 
 /**