diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 0306303be372..e5afa222c213 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -187,7 +187,8 @@ static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 	prz->ecc_block_size = 128;
 	prz->ecc_size = ecc_size;
 
-	ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
+	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_size,
+				  prz->ecc_block_size + prz->ecc_size);
 	ecc_total = (ecc_blocks + 1) * prz->ecc_size;
 	if (ecc_total >= prz->buffer_size) {
 		pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",