diff --git a/AugmentedRealityGo/ARGoController.cpp b/AugmentedRealityGo/ARGoController.cpp
index 9c243a9..92c4d2a 100644
--- a/AugmentedRealityGo/ARGoController.cpp
+++ b/AugmentedRealityGo/ARGoController.cpp
@@ -100,10 +100,13 @@ void ARGoController::startAR()
 		}else if(command == "komi"){
 
 		}else if(command == "play"){
-			if(arguments.size() == 3)
-				board.addVirtualStone(arguments[2], arguments[1]);
-			else
+			if(arguments.size() == 3){
+				if(!board.addVirtualStone(arguments[2], arguments[1])){
+					response = "? invalid play move";
+				}
+			}else{
 				response = "? invalid play move";
+			}
 
 		}else if(command == "genmove"){
 			char color;
diff --git a/AugmentedRealityGo/ARGraphicController.cpp b/AugmentedRealityGo/ARGraphicController.cpp
index 6653217..c43fd94 100644
--- a/AugmentedRealityGo/ARGraphicController.cpp
+++ b/AugmentedRealityGo/ARGraphicController.cpp
@@ -485,8 +485,12 @@ void ARGraphicController::keyFunc(unsigned char key, int x, int y)
 
 			if(board->checkNewBoardState(newRealBoardStones, newMoveColor)){
 
-				board->addRealStone(board->newMoveIndex, newMoveColor);
-				genMove = false;
+				if(!board->addRealStone(board->newMoveIndex, newMoveColor)){
+					//not a valid move
+					fprintf(stderr, "ERROR: Invalid move\n");
+				}else{
+					genMove = false;
+				}
 			}
 
 			
diff --git a/AugmentedRealityGo/GamePlayUtils/FuegoAssistant.cpp b/AugmentedRealityGo/GamePlayUtils/FuegoAssistant.cpp
index 53ee084..71dac61 100644
--- a/AugmentedRealityGo/GamePlayUtils/FuegoAssistant.cpp
+++ b/AugmentedRealityGo/GamePlayUtils/FuegoAssistant.cpp
@@ -144,7 +144,7 @@ bool FuegoAssistant::estimateTerritory(int color)
 
 }
 
-void FuegoAssistant::addMove(std::string move, int color){
+bool FuegoAssistant::addMove(std::string move, int color){
 	//realStones[stone_index] = color;
 	string command;
 	if(color == COLOR_BLACK)
@@ -157,9 +157,13 @@ void FuegoAssistant::addMove(std::string move, int color){
 	string readLine;
 	do{
 		getline(readFromFuego, readLine);
-	}while(readLine[0]!='=');
-	
+	}while(readLine[0]!='=' && readLine[0]!='?');
 
+	if(readLine[0] == '?'){
+		return false;
+	}
+	
+	return true;
 	//getBookPositions();
 }
 
diff --git a/AugmentedRealityGo/GamePlayUtils/FuegoAssistant.h b/AugmentedRealityGo/GamePlayUtils/FuegoAssistant.h
index 85669c8..6082f2a 100644
--- a/AugmentedRealityGo/GamePlayUtils/FuegoAssistant.h
+++ b/AugmentedRealityGo/GamePlayUtils/FuegoAssistant.h
@@ -27,7 +27,7 @@ class FuegoAssistant
 	void clear_board();
 	void genMove(std::string color);
 	
-	void addMove(std::string move, int color);
+	bool addMove(std::string move, int color);
 	void showBoard();
 	bool sendCommandWithEmptyResponse(std::string command, std::string& readLine);
 
diff --git a/AugmentedRealityGo/GamePlayUtils/GoBoard.cpp b/AugmentedRealityGo/GamePlayUtils/GoBoard.cpp
index cbbfc31..d955b42 100644
--- a/AugmentedRealityGo/GamePlayUtils/GoBoard.cpp
+++ b/AugmentedRealityGo/GamePlayUtils/GoBoard.cpp
@@ -45,24 +45,29 @@ void GoBoard::changeTurn()
 	newMoveIsMade = true;
 }
 
-void GoBoard::addVirtualStone(std::string move, std::string color)
+bool GoBoard::addVirtualStone(std::string move, std::string color)
 {
+	//check if this is valid move first
+	if(!fuego->addMove(move, helper::convert_string_color(color)))
+		return false;
 	int stone_index = helper::convert_string_move(move);
 	//std::cout<<"#add virtual stone at: "<<stone_index<<std::endl;
 	if(color == "black" || color =="b")
 		virtualStones[stone_index] = COLOR_BLACK;
 	else if(color =="white"|| color =="w")
 		virtualStones[stone_index] = COLOR_WHITE;
-	fuego->addMove(move, helper::convert_string_color(color));
+	
 	changeTurn();
+	return true;
 }
 
-void GoBoard::addRealStone(int stone_index, int color){
-
+bool GoBoard::addRealStone(int stone_index, int color){
+	//check if this is valid move first
+	if(!fuego->addMove(helper::convert_index_move(stone_index), color))
+		return false;
 	realStones[stone_index] = color;
-
-	fuego->addMove(helper::convert_index_move(stone_index), color);
 	changeTurn();
+	return true;
 }
 
 
diff --git a/AugmentedRealityGo/GamePlayUtils/GoBoard.h b/AugmentedRealityGo/GamePlayUtils/GoBoard.h
index 3213997..91ba69f 100644
--- a/AugmentedRealityGo/GamePlayUtils/GoBoard.h
+++ b/AugmentedRealityGo/GamePlayUtils/GoBoard.h
@@ -26,8 +26,8 @@ class GoBoard
 
 	//add stones
 	void changeTurn();
-    void addVirtualStone(std::string move, std::string color);
-	void addRealStone(int stone_index, int color);
+    bool addVirtualStone(std::string move, std::string color);
+	bool addRealStone(int stone_index, int color);
 
 	//return the color of current turn
 	int getMoveTurnColor();