diff --git a/test/Polar_test.cc b/test/Polar_test.cc
index 9e244f2..ba65946 100644
--- a/test/Polar_test.cc
+++ b/test/Polar_test.cc
@@ -2,6 +2,7 @@
 #include <gtest/gtest.h>
 #include <limits>
 #include <math.h>
+#include <chrono>
 
 #include "Polar.h"
 #include "Spherical.h"
diff --git a/test/Spherical16_test.cc b/test/Spherical16_test.cc
index e9fbc40..8eea700 100644
--- a/test/Spherical16_test.cc
+++ b/test/Spherical16_test.cc
@@ -2,6 +2,7 @@
 #include <gtest/gtest.h>
 #include <limits>
 #include <math.h>
+#include <chrono>
 
 #include "Spherical.h"
 #include "Vector3.h"
diff --git a/test/SphericalSingle_test.cc b/test/SphericalSingle_test.cc
index 7840d77..3dedb31 100644
--- a/test/SphericalSingle_test.cc
+++ b/test/SphericalSingle_test.cc
@@ -2,6 +2,7 @@
 #include <gtest/gtest.h>
 #include <limits>
 #include <math.h>
+#include <chrono>
 
 #include "Spherical.h"