1 files changed, 14 insertions, 7 deletions
diff --git a/src/search.c b/src/search.c
index 6c8a945..e0339cf 100755
--- a/src/search.c
+++ b/src/search.c
@@ -943,8 +943,9 @@ QSearchFromCheckNoStandPat(IN SEARCHER_THREAD_CONTEXT *ctx,
     uMoveCount = MOVE_COUNT(ctx, ctx->uPly);
     if (uMoveCount > 0)
     {
-        // Consider extending the number of qsearch plies for our opponent
-        // if this looks good.
+        // Consider extending the number of qsearch check-generating
+        // plies for our opponent if this looks good -- we have not
+        // yet been able to stand pat and they might mate us.
         if ((pf->uQsearchDepth < pf->uQsearchCheckDepth) &&
             (pf->uQsearchDepth < g_uIterateDepth / 4) &&
             (pf->fCouldStandPat[pos->uToMove] == FALSE) &&
@@ -1144,11 +1145,17 @@ QSearch(IN SEARCHER_THREAD_CONTEXT *ctx,
     // If that Eval (above) was full (i.e. not lazy) it may have set
     // en prise and trapped piece indicators.  Likewise, other nodes
     // at this depth may have set en prise piece hints.  If these are
-    // set and valid, it means this is not a "quiet" position.  If the
-    // side on the move has not been able to stand pat yet, don't let
-    // them now -- force them to play a move and recurse.
-    if (0 != ValueOfMaterialInTroubleDespiteMove(ctx, pos->uToMove) &&
-        FALSE == ctx->sSearchFlags.fCouldStandPat[pos->uToMove])
+    // set and valid, it means this is not a "quiet" position -- don't
+    // let this side stand pat, force them to play a move and recurse.
+    // This is deliberately independent of fCouldStandPat: whether an
+    // ancestor node in this qsearch line had a moment of safety says
+    // nothing about whether *this* node's material danger is real --
+    // a hanging piece doesn't stop hanging because the position was
+    // quiet three plies ago. fCouldStandPat's job is different (see
+    // its other uses: deciding whether a *whole line* looks forcing
+    // enough to justify extra qsearch depth/breadth), not gating
+    // per-node stand-pat correctness.
+    if (0 != ValueOfMaterialInTroubleDespiteMove(ctx, pos->uToMove))
     {
         iBestScore = iAlpha;
     }