diff --git a/src/blockchain_db/lmdb/db_lmdb.cpp b/src/blockchain_db/lmdb/db_lmdb.cpp
index e8667adcf..6eb5501b7 100644
--- a/src/blockchain_db/lmdb/db_lmdb.cpp
+++ b/src/blockchain_db/lmdb/db_lmdb.cpp
@@ -163,7 +163,15 @@ int BlockchainLMDB::compare_string(const MDB_val *a, const MDB_val *b)
 {
   const char *va = (const char*) a->mv_data;
   const char *vb = (const char*) b->mv_data;
-  return strcmp(va, vb);
+  const size_t sz = std::min(a->mv_size, b->mv_size);
+  int ret = strncmp(va, vb, sz);
+  if (ret)
+    return ret;
+  if (a->mv_size < b->mv_size)
+    return -1;
+  if (a->mv_size > b->mv_size)
+    return 1;
+  return 0;
 }
 
 }