diff --git a/test/sensor_host_unittest.cpp b/test/sensor_host_unittest.cpp
index 8bb9cc7..8559081 100644
--- a/test/sensor_host_unittest.cpp
+++ b/test/sensor_host_unittest.cpp
@@ -11,6 +11,11 @@
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
+namespace pid_control
+{
+namespace
+{
+
 using ::testing::IsNull;
 using ::testing::Return;
 using ::testing::StrEq;
@@ -105,3 +110,6 @@
     // Verify it was updated within the last second.
     EXPECT_TRUE(duration < 1);
 }
+
+} // namespace
+} // namespace pid_control