diff --git a/block/partitions/mac.c b/block/partitions/mac.c
index df03ca428e15..f372392af95b 100644
--- a/block/partitions/mac.c
+++ b/block/partitions/mac.c
@@ -97,8 +97,8 @@ int mac_partition(struct parsed_partitions *state)
 		if (be16_to_cpu(part->signature) != MAC_PARTITION_MAGIC)
 			break;
 		put_partition(state, slot,
-			be32_to_cpu(part->start_block) * (secsize/512),
-			be32_to_cpu(part->block_count) * (secsize/512));
+			(sector_t)be32_to_cpu(part->start_block) * (secsize/512),
+			(sector_t)be32_to_cpu(part->block_count) * (secsize/512));
 
 		if (!strncasecmp(part->type, "Linux_RAID", 10))
 			state->parts[slot].flags = ADDPART_FLAG_RAID;