diff --git a/functions/core_math_accuracy_test.cpp b/functions/core_math_accuracy_test.cpp
index ce900e745e..efe0e365c2 100644
--- a/functions/core_math_accuracy_test.cpp
+++ b/functions/core_math_accuracy_test.cpp
@@ -20,8 +20,6 @@ using namespace principia::functions::_multiprecision;
 using namespace principia::testing_utilities::_approximate_quantity;
 using namespace principia::testing_utilities::_is_near;
 
-namespace {
-
 class CoreMathAccuracyTest : public ::testing::Test {
  protected:
   static double ULPDistance(cpp_bin_float_50 const& actual,
@@ -76,6 +74,5 @@ TEST_F(CoreMathAccuracyTest, SinCos) {
 
 #endif
 
-}  // namespace
 }  // namespace functions
 }  // namespace principia
diff --git a/functions/sin_cos_test.cpp b/functions/sin_cos_test.cpp
index acc589db13..de6b9a3f1d 100644
--- a/functions/sin_cos_test.cpp
+++ b/functions/sin_cos_test.cpp
@@ -19,7 +19,7 @@
 // below.
 
 namespace principia {
-namespace {
+namespace functions_test {
 
 using namespace boost::multiprecision;
 using namespace principia::functions::_multiprecision;
@@ -147,5 +147,5 @@ TEST_F(SinCosTest, HardReduction) {
               AlmostEquals(-4.687165924254627611122582801963884e-19, 0));
 }
 
-}  // namespace
+}  // namespace functions_test
 }  // namespace principia
diff --git a/functions/std_accuracy_test.cpp b/functions/std_accuracy_test.cpp
index fdcbee305f..10467eeea0 100644
--- a/functions/std_accuracy_test.cpp
+++ b/functions/std_accuracy_test.cpp
@@ -3,6 +3,7 @@
 #include <limits>
 #include <random>
 
+#include "functions/multiprecision.hpp"
 #include "glog/logging.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
@@ -18,6 +19,7 @@ namespace _multiprecision {
 
 using ::testing::AnyOf;
 using namespace boost::multiprecision;
+using namespace principia::functions::_multiprecision;
 using namespace principia::quantities::_si;
 using namespace principia::testing_utilities::_almost_equals;
 using namespace principia::testing_utilities::_approximate_quantity;