diff --git a/doc/jsonrpc.md b/doc/jsonrpc.md
index ba9dbe4e6..d2f053974 100644
--- a/doc/jsonrpc.md
+++ b/doc/jsonrpc.md
@@ -1558,9 +1558,9 @@ name                    | Optional | string      | Bdev name to use
 block_size              | Required | number      | Block size in bytes
 num_blocks              | Required | number      | Number of blocks
 uuid                    | Optional | string      | UUID of new bdev
-md_size                 | Optional | number      | Metadata size in bytes
-dif_type                | Optional | number      | Protection information type (0, 1, 2 or 3). Default: 0 - no protection.
-dif_is_head_of_md       | Optional | boolean     | Protection information is in the first 8 bytes of MD. Default: in the last 8 bytes.
+md_size                 | Optional | number      | Metadata size for this bdev. Default=0.
+dif_type                | Optional | number      | Protection information type. Parameter --md-size needs to be set along --dif-type. Default=0 - no protection.
+dif_is_head_of_md       | Optional | boolean     | Protection information is in the first 8 bytes of metadata. Default=false.
 
 ### Result
 
diff --git a/module/bdev/null/bdev_null_rpc.c b/module/bdev/null/bdev_null_rpc.c
index f3a433e75..08bdb2897 100644
--- a/module/bdev/null/bdev_null_rpc.c
+++ b/module/bdev/null/bdev_null_rpc.c
@@ -120,6 +120,12 @@ rpc_bdev_null_create(struct spdk_jsonrpc_request *request,
 		goto cleanup;
 	}
 
+	if (req.dif_type != SPDK_DIF_DISABLE && !req.md_size) {
+		spdk_jsonrpc_send_error_response(request, -EINVAL,
+						 "Interleaved metadata size should be set for DIF");
+		goto cleanup;
+	}
+
 	opts.name = req.name;
 	opts.uuid = uuid;
 	opts.num_blocks = req.num_blocks;
diff --git a/scripts/rpc.py b/scripts/rpc.py
index 87957af29..944bcd948 100755
--- a/scripts/rpc.py
+++ b/scripts/rpc.py
@@ -323,6 +323,9 @@ if __name__ == "__main__":
 
     def bdev_null_create(args):
         num_blocks = (args.total_size * 1024 * 1024) // args.block_size
+        if args.dif_type and not args.md_size:
+            print("ERROR: --md-size must be > 0 when --dif-type is > 0")
+            exit(1)
         print_json(rpc.bdev.bdev_null_create(args.client,
                                              num_blocks=num_blocks,
                                              block_size=args.block_size,
@@ -336,15 +339,16 @@ if __name__ == "__main__":
                               help='Add a bdev with null backend')
     p.add_argument('name', help='Block device name')
     p.add_argument('-u', '--uuid', help='UUID of the bdev')
-    p.add_argument(
-        'total_size', help='Size of null bdev in MB (int > 0)', type=int)
-    p.add_argument('block_size', help='Block size for this bdev', type=int)
+    p.add_argument('total_size', help='Size of null bdev in MB (int > 0). Includes only data blocks.', type=int)
+    p.add_argument('block_size', help='Block size for this bdev.'
+                                      'Should be a sum of block size and metadata size if --md-size is used.', type=int)
     p.add_argument('-m', '--md-size', type=int,
-                   help='Metadata size for this bdev. Default 0')
-    p.add_argument('-t', '--dif-type', type=int, choices=[0, 1, 2, 3],
-                   help='Protection information type. Default: 0 - no protection')
+                   help='Metadata size for this bdev. Default=0.')
+    p.add_argument('-t', '--dif-type', type=int, default=0, choices=[0, 1, 2, 3],
+                   help='Protection information type. Parameter --md-size needs'
+                        'to be set along --dif-type. Default=0 - no protection.')
     p.add_argument('-d', '--dif-is-head-of-md', action='store_true',
-                   help='Protection information is in the first 8 bytes of metadata. Default: in the last 8 bytes')
+                   help='Protection information is in the first 8 bytes of metadata. Default=false.')
     p.set_defaults(func=bdev_null_create)
 
     def bdev_null_delete(args):