diff --git a/lib/libcryptsetup.h b/lib/libcryptsetup.h
index 821b4b80..96cbae3d 100644
--- a/lib/libcryptsetup.h
+++ b/lib/libcryptsetup.h
@@ -368,7 +368,7 @@ struct crypt_params_plain {
  */
 struct crypt_params_luks1 {
 	const char *hash;        /**< hash used in LUKS header */
-	size_t data_alignment;   /**< data alignment in sectors, data offset is multiple of this */
+	size_t data_alignment;   /**< data area alignment in 512B sectors, data offset is multiple of this */
 	const char *data_device; /**< detached encrypted data device or @e NULL */
 };
 
@@ -490,7 +490,7 @@ struct crypt_params_luks2 {
 	const struct crypt_pbkdf_type *pbkdf; /**< PBKDF (and hash) parameters or @e NULL*/
 	const char *integrity;                /**< integrity algorithm or @e NULL */
 	const struct crypt_params_integrity *integrity_params; /**< Data integrity parameters or @e NULL*/
-	size_t data_alignment;   /**< data alignment in sectors, data offset is multiple of this */
+	size_t data_alignment;   /**< data area alignment in 512B sectors, data offset is multiple of this */
 	const char *data_device; /**< detached encrypted data device or @e NULL */
 	uint32_t sector_size;    /**< encryption sector size */
 	const char *label;       /**< header label or @e NULL*/
diff --git a/lib/setup.c b/lib/setup.c
index 61bf3da5..f91de309 100644
--- a/lib/setup.c
+++ b/lib/setup.c
@@ -1572,9 +1572,9 @@ static int _crypt_format_luks2(struct crypt_device *cd,
 		cd->device = NULL;
 		if (device_alloc(&cd->device, params->data_device) < 0)
 			return -ENOMEM;
-		required_alignment = params->data_alignment * sector_size;
+		required_alignment = params->data_alignment * SECTOR_SIZE;
 	} else if (params && params->data_alignment) {
-		required_alignment = params->data_alignment * sector_size;
+		required_alignment = params->data_alignment * SECTOR_SIZE;
 	} else
 		device_topology_alignment(cd->device,
 				       &required_alignment,