diff --git a/test/env_unittest.cpp b/test/env_unittest.cpp
index 665f8a5..8e12e0e 100644
--- a/test/env_unittest.cpp
+++ b/test/env_unittest.cpp
@@ -5,28 +5,46 @@
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
+using ::testing::_;
 using ::testing::Return;
 using ::testing::StrEq;
-using ::testing::StrictMock;
+
+namespace env
+{
+
+// Delegate all calls to getEnv() to the mock
+const char* EnvImpl::get(const char* key) const
+{
+    return mockEnv.get(key);
+}
+
+EnvImpl env_impl;
+
+} // namespace env
+
+TEST(EnvTest, NonExistingEnvReturnsEmptyString)
+{
+    EXPECT_CALL(env::mockEnv, get(_)).WillOnce(Return(nullptr));
+    EXPECT_EQ(std::string(), env::getEnv("NonExistingKey"));
+}
 
 TEST(EnvTest, EmptyEnv)
 {
+    EXPECT_CALL(env::mockEnv, get(StrEq("AVERAGE_power1")))
+        .WillOnce(Return(nullptr));
     EXPECT_FALSE(
         phosphor::utility::isAverageEnvSet(std::make_pair("power", "1")));
 }
 
 TEST(EnvTest, ValidAverageEnv)
 {
-    StrictMock<EnvMock> eMock;
-    envIntf = &eMock;
-
     std::string power = "power";
     std::string one = "1";
     std::string two = "2";
 
-    EXPECT_CALL(eMock, getEnv(StrEq("AVERAGE"), power, one))
+    EXPECT_CALL(env::mockEnv, get(StrEq("AVERAGE_power1")))
         .WillOnce(Return("true"));
-    EXPECT_CALL(eMock, getEnv(StrEq("AVERAGE"), power, two))
+    EXPECT_CALL(env::mockEnv, get(StrEq("AVERAGE_power2")))
         .WillOnce(Return("bar"));
 
     EXPECT_TRUE(phosphor::utility::isAverageEnvSet(std::make_pair(power, one)));