diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 27703aad287a..24a015513b40 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -460,7 +460,8 @@ MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes)
 	}
 
 	if (nbytes > 0)
-		nbits -= count_leading_zeros(*(u8 *)(sg_virt(sgl) + lzeros));
+		nbits -= count_leading_zeros(*(u8 *)(sg_virt(sgl) + lzeros)) -
+			(BITS_PER_LONG - 8);
 
 	nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
 	val = mpi_alloc(nlimbs);