diff --git a/src/ray/object_manager/test/object_manager_stress_test.cc b/src/ray/object_manager/test/object_manager_stress_test.cc
index 013c5172d..ad871ef0f 100644
--- a/src/ray/object_manager/test/object_manager_stress_test.cc
+++ b/src/ray/object_manager/test/object_manager_stress_test.cc
@@ -1,3 +1,5 @@
+#include <unistd.h>
+
 #include <chrono>
 #include <iostream>
 #include <random>
diff --git a/src/ray/object_manager/test/object_manager_test.cc b/src/ray/object_manager/test/object_manager_test.cc
index 3a1626c93..e5e9071c1 100644
--- a/src/ray/object_manager/test/object_manager_test.cc
+++ b/src/ray/object_manager/test/object_manager_test.cc
@@ -1,3 +1,5 @@
+#include <unistd.h>
+
 #include <iostream>
 #include <thread>
 
diff --git a/src/ray/util/test_util.h b/src/ray/util/test_util.h
index 79971bba9..473e48544 100644
--- a/src/ray/util/test_util.h
+++ b/src/ray/util/test_util.h
@@ -1,6 +1,8 @@
 #ifndef RAY_UTIL_TEST_UTIL_H
 #define RAY_UTIL_TEST_UTIL_H
 
+#include <unistd.h>
+
 #include <string>
 
 #include "ray/common/buffer.h"