diff --git a/src/tests/kits/locale/DateFormatTest.cpp b/src/tests/kits/locale/DateFormatTest.cpp
index 9b25d5a7fa..a15be10e8b 100644
--- a/src/tests/kits/locale/DateFormatTest.cpp
+++ b/src/tests/kits/locale/DateFormatTest.cpp
@@ -338,6 +338,9 @@ DateFormatTest::TestDayNames()
 }
 
 
+namespace BPrivate {
+
+
 std::ostream& operator<<(std::ostream& stream, const BDate& date)
 {
 	stream << date.Year();
@@ -362,6 +365,9 @@ std::ostream& operator<<(std::ostream& stream, const BTime& date)
 }
 
 
+} // namespace BPrivate
+
+
 void
 DateFormatTest::TestParseDate()
 {