--- a/c++/include/objtools/blast/seqdb_writer/writedb_lmdb.hpp
+++ b/c++/include/objtools/blast/seqdb_writer/writedb_lmdb.hpp
@@ -51,9 +51,15 @@ BEGIN_NCBI_SCOPE
 #ifdef NCBI_OS_MSWIN
 #define DEFAULT_LMDB_MAP_SIZE 500000
 #define DEFAULT_TAXID_MAP_SIZE 500000
+#elif defined(__mips__)
+#define DEFAULT_LMDB_MAP_SIZE (640 * 1024 * 1024)
+#define DEFAULT_TAXID_MAP_SIZE (640 * 1024 * 1024)
+#elif NCBI_PLATFORM_BITS < 64
+#define DEFAULT_LMDB_MAP_SIZE (750 * 1000 * 1000)
+#define DEFAULT_TAXID_MAP_SIZE (750 * 1000 * 1000)
 #else
-#define DEFAULT_LMDB_MAP_SIZE 300000000000
-#define DEFAULT_TAXID_MAP_SIZE 100000000000
+#define DEFAULT_LMDB_MAP_SIZE (20UL * 1000 * 1000 * 1000)
+#define DEFAULT_TAXID_MAP_SIZE (20UL * 1000 * 1000 * 1000)
 #endif
 
 /// This class supports creation of a string accession to integer OID
