diff --git a/src/thread.h b/src/thread.h
index 5c169ee9..fd28ddf7 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -46,7 +46,7 @@ const int THREAD_MAX = 8;
 struct SplitPoint {
   SplitPoint *parent;
   Position pos;
-  SearchStack sstack[THREAD_MAX][PLY_MAX];
+  SearchStack sstack[THREAD_MAX][PLY_MAX_PLUS_2];
   SearchStack *parentSstack;
   int ply;
   Depth depth;