diff --git a/phosphor-regulators/test/rail_tests.cpp b/phosphor-regulators/test/rail_tests.cpp
index 5781973..b0a3466 100644
--- a/phosphor-regulators/test/rail_tests.cpp
+++ b/phosphor-regulators/test/rail_tests.cpp
@@ -33,6 +33,7 @@
 #include <utility>
 #include <vector>
 
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
 using namespace phosphor::power::regulators;