diff --git a/src/position.cpp b/src/position.cpp
index 15ccb483..5a98821d 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -149,6 +149,7 @@ void Position::init() {
 
   for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr)
   {
+      Zobrist::castling[cr] = 0;
       Bitboard b = cr;
       while (b)
       {
diff --git a/src/ucioption.cpp b/src/ucioption.cpp
index 35c907ae..fd6c46d2 100644
--- a/src/ucioption.cpp
+++ b/src/ucioption.cpp
@@ -19,7 +19,7 @@
 
 #include <algorithm>
 #include <cassert>
-#include <sstream>
+#include <ostream>
 
 #include "misc.h"
 #include "thread.h"