diff --git a/coding/file_reader.cpp b/coding/file_reader.cpp
index 6a7d0231a4..e19920e255 100644
--- a/coding/file_reader.cpp
+++ b/coding/file_reader.cpp
@@ -128,14 +128,13 @@ void FileReader::CheckPosAndSize(uint64_t pos, uint64_t size) const
 {
   uint64_t const allSize1 = Size();
   bool const ret1 = (pos + size <= allSize1);
-  ASSERT(ret1, (pos, size, allSize1));
+  if (!ret1)
+    MYTHROW(Reader::SizeException, (pos, size, allSize1));
 
   uint64_t const allSize2 = m_fileData->Size();
   bool const ret2 = (m_offset + pos + size <= allSize2);
-  ASSERT(ret2, (m_offset, pos, size, allSize2));
-
-  if (!ret1 || !ret2)
-    MYTHROW(Reader::SizeException, (pos, size));
+  if (!ret2)
+    MYTHROW(Reader::SizeException, (pos, size, allSize2));
 }
 
 void FileReader::SetOffsetAndSize(uint64_t offset, uint64_t size)