diff --git a/libraries/liblmdb/CHANGES b/libraries/liblmdb/CHANGES
index ee99256b71..0c1295d3bd 100644
--- a/libraries/liblmdb/CHANGES
+++ b/libraries/liblmdb/CHANGES
@@ -6,6 +6,7 @@ LMDB 0.9.18 Release Engineering
 	Fix MDB_APPENDDUP vs. rewrite(single item) (ITS#8334)
 	Fix mdb_copy of large files on Windows
 	Fix subcursor move after delete (ITS#8355)
+	Fix mdb_midl_shirnk off-by-one (ITS#8363)
 	Check for utf8_to_utf16 failures (ITS#7992)
 	Catch strdup failure in mdb_dbi_open
 	Build
diff --git a/libraries/liblmdb/midl.c b/libraries/liblmdb/midl.c
index 57a9d4920e..5c6d841a7a 100644
--- a/libraries/liblmdb/midl.c
+++ b/libraries/liblmdb/midl.c
@@ -120,7 +120,7 @@ void mdb_midl_shrink( MDB_IDL *idp )
 {
 	MDB_IDL ids = *idp;
 	if (*(--ids) > MDB_IDL_UM_MAX &&
-		(ids = realloc(ids, (MDB_IDL_UM_MAX+1) * sizeof(MDB_ID))))
+		(ids = realloc(ids, (MDB_IDL_UM_MAX+2) * sizeof(MDB_ID))))
 	{
 		*ids++ = MDB_IDL_UM_MAX;
 		*idp = ids;