diff --git a/DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java b/DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java
index 7924cc6..9f4e276 100644
--- a/DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java
+++ b/DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java
@@ -745,18 +745,37 @@ public class DroidComputerPlayer {
 
     private final void reportMove(String bestMove, Move nextPonderMove) {
         SearchRequest sr = searchRequest;
+        boolean canPonder = true;
 
         // Claim draw if appropriate
         if (statScore <= 0) {
             String drawClaim = canClaimDraw(sr.currPos, sr.posHashList, sr.posHashListSize,
                                             TextIO.UCIstringToMove(bestMove));
-            if (drawClaim != "")
+            if (drawClaim != "") {
                 bestMove = drawClaim;
+                canPonder = false;
+            }
         }
         // Accept draw offer if engine is losing
         if (sr.drawOffer && !statIsMate && (statScore <= -300)) {
             bestMove = "draw accept";
+            canPonder = false;
         }
+
+        if (canPonder) {
+            Move bestM = TextIO.stringToMove(sr.currPos, bestMove);
+            if ((bestM == null) || !TextIO.isValid(sr.currPos, bestM, null))
+                canPonder = false;
+            if (canPonder) {
+                Position tmpPos = new Position(sr.currPos);
+                UndoInfo ui = new UndoInfo();
+                tmpPos.makeMove(bestM, ui);
+                if (!TextIO.isValid(tmpPos, nextPonderMove, null))
+                    canPonder = false;
+            }
+        }
+        if (!canPonder)
+            nextPonderMove = null;
         listener.notifySearchResult(sr.searchId, bestMove, nextPonderMove);
     }
 
diff --git a/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java b/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
index 051be19..a8ce6b4 100644
--- a/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
+++ b/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
@@ -673,6 +673,8 @@ public class DroidChessController {
                 for (Move m : pv.pv) {
                     if (m == null)
                         break;
+                    if (!TextIO.isValid(tmpPos, m, null))
+                        break;
                     String moveStr = TextIO.moveToString(tmpPos, m, false);
                     buf.append(String.format(" %s", moveStr));
                     tmpPos.makeMove(m, ui);
diff --git a/DroidFish/src/org/petero/droidfish/gamelogic/Game.java b/DroidFish/src/org/petero/droidfish/gamelogic/Game.java
index 22b8904..a7f0833 100644
--- a/DroidFish/src/org/petero/droidfish/gamelogic/Game.java
+++ b/DroidFish/src/org/petero/droidfish/gamelogic/Game.java
@@ -124,25 +124,13 @@ public class Game {
         }
 
         Move m = TextIO.UCIstringToMove(str);
-        if (m != null) {
-            ArrayList<Move> moves = new MoveGen().pseudoLegalMoves(currPos());
-            moves = MoveGen.removeIllegal(currPos(), moves);
-            boolean legal = false;
-            for (int i = 0; i < moves.size(); i++) {
-                if (m.equals(moves.get(i))) {
-                    legal = true;
-                    break;
-                }
-            }
-            if (!legal)
+        if (m != null)
+            if (!TextIO.isValid(currPos(), m, null))
                 m = null;
-        }
-        if (m == null) {
+        if (m == null)
             m = TextIO.stringToMove(currPos(), str);
-        }
-        if (m == null) {
+        if (m == null)
             return false;
-        }
 
         addToGameTree(m, pendingDrawOffer ? "draw offer" : "");
         return true;
diff --git a/DroidFish/src/org/petero/droidfish/gamelogic/TextIO.java b/DroidFish/src/org/petero/droidfish/gamelogic/TextIO.java
index 08540dc..e006fbe 100644
--- a/DroidFish/src/org/petero/droidfish/gamelogic/TextIO.java
+++ b/DroidFish/src/org/petero/droidfish/gamelogic/TextIO.java
@@ -422,6 +422,24 @@ public class TextIO {
         }
     }
 
+    /**
+     * Decide if move is valid in position pos.
+     * @param pos   Position for which to test move.
+     * @param move  The move to check for validity.
+     * @param moves If non-null, list of valid moves in position pos.
+     * @return True if move is valid in position pos, false otherwise.
+     */
+    public static final boolean isValid(Position pos, Move move, ArrayList<Move> moves) {
+        if (moves == null) {
+            moves = new MoveGen().pseudoLegalMoves(pos);
+            moves = MoveGen.removeIllegal(pos, moves);
+        }
+        for (int i = 0; i < moves.size(); i++)
+            if (move.equals(moves.get(i)))
+                return true;
+        return false;
+    }
+
     private final static class MoveInfo {
         int piece;                  // -1 for unspecified
         int fromX, fromY, toX, toY; // -1 for unspecified