diff --git a/include/boost/logic/tribool.hpp b/include/boost/logic/tribool.hpp
index 2cc501c..229feb4 100644
--- a/include/boost/logic/tribool.hpp
+++ b/include/boost/logic/tribool.hpp
@@ -336,7 +336,7 @@ inline tribool operator==(tribool x, tribool y)
   if (indeterminate(x) || indeterminate(y))
     return indeterminate;
   else
-    return x && y || !x && !y;
+    return (x && y) || (!x && !y);
 }
 
 /**
@@ -399,7 +399,7 @@ inline tribool operator!=(tribool x, tribool y)
   if (indeterminate(x) || indeterminate(y))
     return indeterminate;
   else
-    return !(x && y || !x && !y);
+    return !((x && y) || (!x && !y));
 }
 
 /**
diff --git a/test/tribool_io_test.cpp b/test/tribool_io_test.cpp
index d7254f1..84bce90 100644
--- a/test/tribool_io_test.cpp
+++ b/test/tribool_io_test.cpp
@@ -8,6 +8,7 @@
 #include <sstream>
 #include <string>
 #include <iostream>
+#include <ios>     // for std::boolalpha
 
 #ifndef BOOST_NO_STD_LOCALE
 #  include <locale>