diff --git a/tests/unit-tests/security/identity-fixture.cpp b/tests/unit-tests/security/identity-fixture.cpp
index 04589bc..38c85a8 100644
--- a/tests/unit-tests/security/identity-fixture.cpp
+++ b/tests/unit-tests/security/identity-fixture.cpp
@@ -20,20 +20,18 @@
  */
 
 #include "security/key-chain.hpp"
-
+#include "../util/test-home-environment-fixture.hpp"
 #include "boost-test.hpp"
 
 namespace ndn {
 namespace security {
 
-class IdentityFixture
+class IdentityFixture : public util::TestHomeEnvironmentFixture
 {
 public:
   IdentityFixture()
   {
     // initialize KeyChain from TEST_HOME
-    if (std::getenv("TEST_HOME"))
-      m_HOME = std::getenv("TEST_HOME");
     setenv("TEST_HOME", "tests/unit-tests/security/config-file-home", 1);
 
     KeyChain keyChain("sqlite3", "file");
@@ -71,11 +69,6 @@
     // XXX This has no effect if oldDefaultIdentity doesn't exist.
     //     newIdentity would be kept as default.
     keyChain.deleteIdentity(m_newIdentity);
-
-    if (!m_HOME.empty())
-      setenv("TEST_HOME", m_HOME.c_str(), 1);
-    else
-      unsetenv("TEST_HOME");
   }
 
 private:
diff --git a/tests/unit-tests/security/test-keychain.cpp b/tests/unit-tests/security/test-keychain.cpp
index dad7e75..bb3af0c 100644
--- a/tests/unit-tests/security/test-keychain.cpp
+++ b/tests/unit-tests/security/test-keychain.cpp
@@ -20,6 +20,7 @@
  */
 
 #include "security/key-chain.hpp"
+#include "../util/test-home-environment-fixture.hpp"
 #include <boost/filesystem.hpp>
 
 #include "boost-test.hpp"
@@ -29,28 +30,7 @@
 
 using std::vector;
 
-class KeychainConfigFileFixture
-{
-public:
-  KeychainConfigFileFixture()
-  {
-    if (std::getenv("TEST_HOME"))
-      m_HOME = std::getenv("TEST_HOME");
-  }
-
-  ~KeychainConfigFileFixture()
-  {
-    if (!m_HOME.empty())
-      setenv("TEST_HOME", m_HOME.c_str(), 1);
-    else
-      unsetenv("TEST_HOME");
-  }
-
-protected:
-  std::string m_HOME;
-};
-
-BOOST_FIXTURE_TEST_SUITE(SecurityTestKeyChain, KeychainConfigFileFixture)
+BOOST_FIXTURE_TEST_SUITE(SecurityTestKeyChain, util::TestHomeEnvironmentFixture)
 
 BOOST_AUTO_TEST_CASE(ConstructorNormalConfig)
 {