diff --git a/lib/genalloc.c b/lib/genalloc.c
index ca208a9..5492043 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -178,7 +178,7 @@
 	struct gen_pool_chunk *chunk;
 	int nbits = size >> pool->min_alloc_order;
 	int nbytes = sizeof(struct gen_pool_chunk) +
-				(nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE;
+				BITS_TO_LONGS(nbits) * sizeof(long);
 
 	chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid);
 	if (unlikely(chunk == NULL))