diff --git a/include/spdk/opal_spec.h b/include/spdk/opal_spec.h
index 5605f8e77..64d355354 100644
--- a/include/spdk/opal_spec.h
+++ b/include/spdk/opal_spec.h
@@ -35,6 +35,7 @@
 #define SPDK_OPAL_SPEC_H
 
 #include "spdk/stdinc.h"
+#include "spdk/assert.h"
 
 /*
  * TCG Storage Architecture Core Spec v2.01 r1.00
@@ -189,12 +190,13 @@ struct spdk_d0_header {
 	uint32_t reserved_1;
 	uint8_t vendor_specfic[32];
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_d0_header) == 48, "Incorrect size");
 
 /*
  * TCG Storage Architecture Core Spec v2.01 r1.00
  * Table-42 TPer Feature Descriptor
  */
-struct spdk_d0_tper_features {
+struct __attribute__((packed)) spdk_d0_tper_features {
 	uint16_t feature_code;
 	uint8_t reserved_0 : 4;
 	uint8_t version : 4;
@@ -208,21 +210,21 @@ struct spdk_d0_tper_features {
 	uint8_t comid_management : 1;
 	uint8_t reserved_2 : 1;
 
-	uint32_t reserved_3;
+	uint8_t reserved_3[3];
 	uint32_t reserved_4;
 	uint32_t reserved_5;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_d0_tper_features) == 16, "Incorrect size");
 
 /*
  * TCG Storage Architecture Core Spec v2.01 r1.00
  * Table-43 Locking Feature Descriptor
  */
-struct spdk_d0_locking_features {
+struct __attribute__((packed)) spdk_d0_locking_features {
 	uint16_t feature_code;
 	uint8_t reserved_0 : 4;
 	uint8_t version : 4;
 	uint8_t length;
-
 	uint8_t locking_supported : 1;
 	uint8_t locking_enabled : 1;
 	uint8_t locked : 1;
@@ -232,22 +234,22 @@ struct spdk_d0_locking_features {
 	uint8_t reserved_1 : 1;
 	uint8_t reserved_2 : 1;
 
-	uint32_t reserved_3;
+	uint8_t reserved_3[3];
 	uint32_t reserved_4;
 	uint32_t reserved_5;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_d0_locking_features) == 16, "Incorrect size");
 
 /*
  * TCG Storage Opal Feature Set Single User Mode v1.00 r2.00
  * 4.2.1 Single User Mode Feature Descriptor
  */
-struct spdk_d0_sum {
+struct __attribute__((packed)) spdk_d0_sum {
 	uint16_t feature_code;
 	uint8_t reserved_0 : 4;
 	uint8_t version : 4;
 	uint8_t length;
 	uint32_t num_locking_objects;
-
 	uint8_t any : 1;
 	uint8_t all : 1;
 	uint8_t policy : 1;
@@ -257,17 +259,17 @@ struct spdk_d0_sum {
 	uint16_t reserved_3;
 	uint32_t reserved_4;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_d0_sum) == 16, "Incorrect size");
 
 /*
  * TCG Storage Opal v2.01 r1.00
  * 3.1.1.4 Geometry Reporting Feature
  */
-struct spdk_d0_geo_features {
+struct __attribute__((packed)) spdk_d0_geo_features {
 	uint16_t feature_code;
 	uint8_t reserved_0 : 4;
 	uint8_t version : 4;
 	uint8_t length;
-
 	uint8_t align : 1;
 	uint8_t reserved_1 : 7;
 	uint8_t reserved_2[7];
@@ -275,28 +277,29 @@ struct spdk_d0_geo_features {
 	uint64_t alignment_granularity;
 	uint64_t lowest_aligned_lba;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_d0_geo_features) == 32, "Incorrect size");
 
 /*
  * TCG Storage Opal Feature Set Additional DataStore Tables v1.00 r1.00
  * 4.1.1 DataStore Table Feature Descriptor
  */
-struct spdk_d0_datastore_features {
+struct __attribute__((packed)) spdk_d0_datastore_features {
 	uint16_t feature_code;
 	uint8_t reserved_0 : 4;
 	uint8_t version : 4;
 	uint8_t length;
-
 	uint16_t reserved_1;
 	uint16_t max_tables;
 	uint32_t max_table_size;
 	uint32_t alignment;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_d0_datastore_features) == 16, "Incorrect size");
 
 /*
  * Opal SSC 1.00 r3.00 Final
  * 3.1.1.4 Opal SSC Feature
  */
-struct spdk_d0_opal_v100 {
+struct __attribute__((packed)) spdk_d0_opal_v100 {
 	uint16_t feature_code;
 	uint8_t reserved_0 : 4;
 	uint8_t version : 4;
@@ -311,30 +314,31 @@ struct spdk_d0_opal_v100 {
 	uint32_t reserved_4;
 	uint32_t reserved_5;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_d0_opal_v100) == 20, "Incorrect size");
 
 /*
  * TCG Storage Opal v2.01 r1.00
  * 3.1.1.4 Geometry Reporting Feature
  * 3.1.1.5 Opal SSC V2.00 Feature
  */
-struct spdk_d0_opal_v200 {
+struct __attribute__((packed)) spdk_d0_opal_v200 {
 	uint16_t featureCode;
 	uint8_t reserved_0 : 4;
 	uint8_t version : 4;
 	uint8_t length;
 	uint16_t base_comid;
 	uint16_t num_comids;
-
 	uint8_t range_crossing : 1;
 	uint8_t reserved_1 : 7;
-
 	uint16_t num_locking_admin_auth; /* Number of Locking SP Admin Authorities Supported */
 	uint16_t num_locking_user_auth;
 	uint8_t initial_pin;
 	uint8_t reverted_pin;
+
 	uint8_t reserved_2;
 	uint32_t reserved_3;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_d0_opal_v200) == 20, "Incorrect size");
 
 /*
  * TCG Storage Architecture Core Spec v2.01 r1.00
@@ -344,33 +348,34 @@ struct spdk_d0_opal_v200 {
 /* CommPacket header format
  * (big-endian)
  */
-struct spdk_opal_compacket {
+struct __attribute__((packed)) spdk_opal_compacket {
 	uint32_t reserved;
 	uint8_t comid[2];
 	uint8_t extended_comid[2];
-
 	uint32_t outstanding_data;
 	uint32_t min_transfer;
 	uint32_t length;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_opal_compacket) == 20, "Incorrect size");
 
 /* packet header format */
-struct spdk_opal_packet {
+struct __attribute__((packed)) spdk_opal_packet {
 	uint32_t session_tsn;
 	uint32_t session_hsn;
 	uint32_t seq_number;
-
 	uint16_t reserved;
 	uint16_t ack_type;
 	uint32_t acknowledgment;
 	uint32_t length;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_opal_packet) == 24, "Incorrect size");
 
 /* data subpacket header */
-struct spdk_opal_data_subpacket {
+struct __attribute__((packed)) spdk_opal_data_subpacket {
 	uint8_t reserved[6];
 	uint16_t kind;
 	uint32_t length;
 };
+SPDK_STATIC_ASSERT(sizeof(struct spdk_opal_data_subpacket) == 12, "Incorrect size");
 
 #endif