diff --git a/src/square.h b/src/square.h
index 8de3f55c..d539e005 100644
--- a/src/square.h
+++ b/src/square.h
@@ -77,20 +77,10 @@ const int FlopMask = 07;
 //// Inline functions
 ////
 
-inline Square operator+ (Square x, int i) { return Square(int(x) + i); }
-inline void operator++ (Square &x, int) { x = Square(int(x) + 1); }
-inline void operator+= (Square &x, int i) { x = Square(int(x) + i); }
-inline Square operator- (Square x, int i) { return Square(int(x) - i); }
-inline void operator-- (Square &x, int) { x = Square(int(x) - 1); }
-inline void operator-= (Square &x, int i) { x = Square(int(x) - i); }
-inline Square operator+ (Square x, SquareDelta i) { return Square(int(x) + i); }
-inline void operator+= (Square &x, SquareDelta i) { x = Square(int(x) + i); }
-inline Square operator- (Square x, SquareDelta i) { return Square(int(x) - i); }
-inline void operator-= (Square &x, SquareDelta i) { x = Square(int(x) - i); }
-
-inline SquareDelta operator- (Square x, Square y) {
-  return SquareDelta(int(x) - int(y));
-}
+inline Square operator+ (Square x, SquareDelta i) { return x + Square(i); }
+inline void operator+= (Square& x, SquareDelta i) { x = x + Square(i); }
+inline Square operator- (Square x, SquareDelta i) { return x - Square(i); }
+inline void operator-= (Square& x, SquareDelta i) { x = x - Square(i); }
 
 inline Square make_square(File f, Rank r) {
   return Square(int(f) | (int(r) << 3));
diff --git a/src/types.h b/src/types.h
index f018311d..ec9f9bb9 100644
--- a/src/types.h
+++ b/src/types.h
@@ -125,6 +125,9 @@ inline T operator* (int i, const T d) { return T(int(d) * i); }
 template<typename T>
 inline T operator/ (const T d, int i) { return T(int(d) / i); }
 
+template<typename T>
+inline T operator- (const T d) { return T(-int(d)); }
+
 template<typename T>
 inline void operator++ (T& d, int) { d = T(int(d) + 1); }