diff --git a/lib/genalloc.c b/lib/genalloc.c
index 604ee0921fb..0218f4b3af3 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -247,7 +247,7 @@ void gen_pool_destroy(struct gen_pool *pool)
 
 		end_bit = (chunk->end_addr - chunk->start_addr) >> order;
 		nbytes = sizeof(struct gen_pool_chunk) +
-				(end_bit + BITS_PER_BYTE - 1) / BITS_PER_BYTE;
+				BITS_TO_LONGS(end_bit) * sizeof(long);
 		bit = find_next_bit(chunk->bits, end_bit, 0);
 		BUG_ON(bit < end_bit);