diff --git a/src/search.cpp b/src/search.cpp
index 88ef5237..38e2ac14 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1860,17 +1860,29 @@ namespace {
       // New best move?
       if (value > sp->bestValue) // Less then 2% of cases
       {
-          lock_grab(&(sp->lock));
+          // Recursive locking, lock current split point and its ancestors to
+          // guarantee thread_should_stop() and sp_update_pv() are race free.
+          SplitPoint* spChain[MAX_THREADS * ACTIVE_SPLIT_POINTS_MAX];
+          int cnt = 0;
+          for (spChain[cnt] = sp; spChain[cnt]; )
+          {
+              lock_grab(&(spChain[cnt++]->lock));
+              spChain[cnt] = spChain[cnt - 1]->parent;
+          }
+
           if (value > sp->bestValue && !TM.thread_should_stop(threadID))
           {
               sp->bestValue = value;
               if (sp->bestValue >= sp->beta)
               {
-                  sp_update_pv(sp->parentSstack, ss, sp->ply);
                   sp->stopRequest = true;
+                  sp_update_pv(sp->parentSstack, ss, sp->ply);
               }
           }
-          lock_release(&(sp->lock));
+
+          // Release locks in reverse order
+          while (cnt > 0)
+              lock_release(&(spChain[--cnt]->lock));
       }
     }
 
@@ -1975,7 +1987,16 @@ namespace {
       // New best move?
       if (value > sp->bestValue) // Less then 2% of cases
       {
-          lock_grab(&(sp->lock));
+          // Recursive locking, lock current split point and its ancestors to
+          // guarantee thread_should_stop() and sp_update_pv() are race free.
+          SplitPoint* spChain[MAX_THREADS * ACTIVE_SPLIT_POINTS_MAX];
+          int cnt = 0;
+          for (spChain[cnt] = sp; spChain[cnt]; )
+          {
+              lock_grab(&(spChain[cnt++]->lock));
+              spChain[cnt] = spChain[cnt - 1]->parent;
+          }
+
           if (value > sp->bestValue && !TM.thread_should_stop(threadID))
           {
               sp->bestValue = value;
@@ -1992,7 +2013,10 @@ namespace {
                       ss[sp->ply].mateKiller = move;
               }
           }
-          lock_release(&(sp->lock));
+
+          // Release locks in reverse order
+          while (cnt > 0)
+              lock_release(&(spChain[--cnt]->lock));
       }
     }