diff --git a/coding/blob_storage.cpp b/coding/blob_storage.cpp
index d35f7e13ba..21995fdaf9 100644
--- a/coding/blob_storage.cpp
+++ b/coding/blob_storage.cpp
@@ -36,21 +36,24 @@ BlobStorage::~BlobStorage()
 
 void BlobStorage::Init()
 {
-  string header(3, ' ');
-  ReadFromPos(*m_pReader, 0, &header[0], 3);
+  uint32_t const HEADER_TAG_SIZE = 3;
+  uint32_t const HEADER_SIZE = 4;
+  string header(HEADER_TAG_SIZE, ' ');
+  ReadFromPos(*m_pReader, 0, &header[0], HEADER_TAG_SIZE);
   if (header != "Blb")
     MYTHROW(BlobStorage::OpenException, (header));
-  m_bitsInChunkSize = ReadPrimitiveFromPos<uint8_t>(*m_pReader, 3);
+
+  m_bitsInChunkSize = ReadPrimitiveFromPos<uint8_t>(*m_pReader, HEADER_TAG_SIZE);
 
   uint64_t const fileSize = m_pReader->Size();
-  uint32_t const blobCount = ReadPrimitiveFromPos<uint32_t>(*m_pReader, fileSize - 4);
+  uint32_t const blobCount = ReadPrimitiveFromPos<uint32_t>(*m_pReader, fileSize - HEADER_SIZE);
   m_blobInfo.Init(PolymorphReader(m_pReader->CreateSubReader(
-                                    fileSize - 4 - 4 * blobCount,
+                                    fileSize - HEADER_SIZE - 4 * blobCount,
                                     4 * blobCount)));
   uint32_t const chunkCount =
       (blobCount > 0 ? (m_blobInfo[blobCount - 1] >> m_bitsInChunkSize) + 1 : 0);
   m_chunkOffset.Init(PolymorphReader(m_pReader->CreateSubReader(
-                                       fileSize - 4 - 4 * blobCount - 4 * chunkCount,
+                                       fileSize - HEADER_SIZE - 4 * blobCount - 4 * chunkCount,
                                        4 * chunkCount)));
 }
 
diff --git a/coding/dd_vector.hpp b/coding/dd_vector.hpp
index 3661c18f64..f31452d6d9 100644
--- a/coding/dd_vector.hpp
+++ b/coding/dd_vector.hpp
@@ -4,6 +4,7 @@
 
 #include "../base/assert.hpp"
 #include "../base/base.hpp"
+#include "../base/exception.hpp"
 #include "../base/src_point.hpp"
 
 #include "../std/type_traits.hpp"
@@ -23,6 +24,8 @@ public:
   typedef TDifference difference_type;
   typedef TReader ReaderType;
 
+  DECLARE_EXCEPTION(OpenException, RootException);
+
   DDVector() : m_Size(0) {}
 
   explicit DDVector(TReader const & reader) : m_reader(reader)
@@ -163,6 +166,8 @@ public:
 private:
   void InitSize()
   {
+    if ((m_reader.Size() % sizeof(T)) != 0)
+      MYTHROW(OpenException, (m_reader.Size(), sizeof(T)));
     // TODO: Check that reader.Size() % sizeof(T) == 0
     m_Size = m_reader.Size() / sizeof(T);
   }