diff --git a/src/gtest-port.cc b/src/gtest-port.cc
index cd3ac9a..3bc404b 100644
--- a/src/gtest-port.cc
+++ b/src/gtest-port.cc
@@ -1174,6 +1174,9 @@
 //
 // The value is considered true iff it's not "0".
 bool BoolFromGTestEnv(const char* flag, bool default_value) {
+#if defined(GTEST_GET_BOOL_FROM_ENV_)
+  return GTEST_GET_BOOL_FROM_ENV_(flag, default_value);
+#endif  // defined(GTEST_GET_BOOL_FROM_ENV_)
   const std::string env_var = FlagToEnvVar(flag);
   const char* const string_value = posix::GetEnv(env_var.c_str());
   return string_value == NULL ?
@@ -1184,6 +1187,9 @@
 // variable corresponding to the given flag; if it isn't set or
 // doesn't represent a valid 32-bit integer, returns default_value.
 Int32 Int32FromGTestEnv(const char* flag, Int32 default_value) {
+#if defined(GTEST_GET_INT32_FROM_ENV_)
+  return GTEST_GET_INT32_FROM_ENV_(flag, default_value);
+#endif  // defined(GTEST_GET_INT32_FROM_ENV_)
   const std::string env_var = FlagToEnvVar(flag);
   const char* const string_value = posix::GetEnv(env_var.c_str());
   if (string_value == NULL) {
@@ -1206,6 +1212,9 @@
 // Reads and returns the string environment variable corresponding to
 // the given flag; if it's not set, returns default_value.
 const char* StringFromGTestEnv(const char* flag, const char* default_value) {
+#if defined(GTEST_GET_STRING_FROM_ENV_)
+  return GTEST_GET_STRING_FROM_ENV_(flag, default_value);
+#endif  // defined(GTEST_GET_STRING_FROM_ENV_)
   const std::string env_var = FlagToEnvVar(flag);
   const char* const value = posix::GetEnv(env_var.c_str());
   return value == NULL ? default_value : value;
diff --git a/test/gtest_unittest.cc b/test/gtest_unittest.cc
index dd7f19f..60aed35 100644
--- a/test/gtest_unittest.cc
+++ b/test/gtest_unittest.cc
@@ -1671,6 +1671,8 @@
   EXPECT_EQ(10, Int32FromGTestEnv("temp", 10));
 }
 
+# if !defined(GTEST_GET_INT32_FROM_ENV_)
+
 // Tests that Int32FromGTestEnv() returns the default value when the
 // environment variable overflows as an Int32.
 TEST(Int32FromGTestEnvTest, ReturnsDefaultWhenValueOverflows) {
@@ -1695,6 +1697,8 @@
   EXPECT_EQ(50, Int32FromGTestEnv("temp", 50));
 }
 
+# endif  // !defined(GTEST_GET_INT32_FROM_ENV_)
+
 // Tests that Int32FromGTestEnv() parses and returns the value of the
 // environment variable when it represents a valid decimal integer in
 // the range of an Int32.