diff --git a/src/move.cpp b/src/move.cpp
index 2a18c1c4..cb6b5dfd 100644
--- a/src/move.cpp
+++ b/src/move.cpp
@@ -135,7 +135,7 @@ const std::string move_to_uci(Move move, bool chess960) {
 }
 
 
-/// Overload the << operator, to make it easier to print moves.
+/// Overload the << operator, to make it easier to print moves
 
 std::ostream& operator << (std::ostream& os, Move m) {
 
@@ -144,9 +144,9 @@ std::ostream& operator << (std::ostream& os, Move m) {
 }
 
 
-/// move_is_ok(), for debugging.
+/// move_is_ok(), for debugging
 
 bool move_is_ok(Move m) {
 
-  return square_is_ok(move_from(m)) && square_is_ok(move_to(m));
+  return move_from(m) != move_to(m); // Catches also MOVE_NONE
 }
diff --git a/src/move.h b/src/move.h
index c4ed9dd8..d06e381a 100644
--- a/src/move.h
+++ b/src/move.h
@@ -207,5 +207,4 @@ extern Move move_from_uci(const Position& pos, const std::string &str);
 extern const std::string move_to_uci(Move m, bool chess960);
 extern bool move_is_ok(Move m);
 
-
 #endif // !defined(MOVE_H_INCLUDED)
diff --git a/src/square.h b/src/square.h
index f89c72ee..46456d06 100644
--- a/src/square.h
+++ b/src/square.h
@@ -177,7 +177,7 @@ inline bool rank_is_ok(Rank r) {
 }
 
 inline bool square_is_ok(Square s) {
-  return file_is_ok(square_file(s)) && rank_is_ok(square_rank(s));
+  return s >= SQ_A1 && s <= SQ_H8;
 }
 
 #endif // !defined(SQUARE_H_INCLUDED)