diff --git a/src/currency_core/blockchain_storage.cpp b/src/currency_core/blockchain_storage.cpp
index 3dcbaed8..0d6d41f8 100644
--- a/src/currency_core/blockchain_storage.cpp
+++ b/src/currency_core/blockchain_storage.cpp
@@ -5709,7 +5709,8 @@ uint64_t blockchain_storage::get_last_n_blocks_timestamps_median(size_t n) const
 
   std::vector<uint64_t> timestamps = get_last_n_blocks_timestamps(n);
   uint64_t median_res = epee::misc_utils::median(timestamps);
-  m_timestamps_median_cache[n] = median_res;
+  if (timestamps.size() == n)
+    m_timestamps_median_cache[n] = median_res;
   return median_res;
 }
 //------------------------------------------------------------------