diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index 77b6d0b69..e69ea6b08 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -853,7 +853,7 @@ difficulty_type Blockchain::get_difficulty_for_next_block()
   }
   else
   {
-    size_t offset = height - std::min < size_t > (height, static_cast<size_t>(DIFFICULTY_BLOCKS_COUNT));
+    uint64_t offset = height - std::min <uint64_t> (height, static_cast<uint64_t>(DIFFICULTY_BLOCKS_COUNT));
     if (offset == 0)
       ++offset;