diff --git a/Piece.cpp b/Piece.cpp
index e49534b..ebeac42 100644
--- a/Piece.cpp
+++ b/Piece.cpp
@@ -54,6 +54,8 @@ std::ostream &operator<<(std::ostream &os, const Piece &piece) {
         break;
     case PieceType::King: typeNum = 'K';
         break;
+    default:
+        return os;
     }
 
     if (piece.color() == PieceColor::Black) {