diff --git a/cpp/src/phonenumbers/geocoding/phonenumber_offline_geocoder.cc b/cpp/src/phonenumbers/geocoding/phonenumber_offline_geocoder.cc
index 750f27b12..55e7ab192 100644
--- a/cpp/src/phonenumbers/geocoding/phonenumber_offline_geocoder.cc
+++ b/cpp/src/phonenumbers/geocoding/phonenumber_offline_geocoder.cc
@@ -17,7 +17,6 @@
 #include "phonenumbers/geocoding/phonenumber_offline_geocoder.h"
 
 #include <algorithm>
-#include <map>
 #include <string>
 
 #include <unicode/unistr.h>  // NOLINT(build/include_order)
@@ -32,7 +31,6 @@ namespace i18n {
 namespace phonenumbers {
 
 using icu::UnicodeString;
-using std::map;
 using std::string;
 
 namespace {
@@ -77,7 +75,7 @@ void PhoneNumberOfflineGeocoder::Init(
 }
 
 PhoneNumberOfflineGeocoder::~PhoneNumberOfflineGeocoder() {
-  STLDeleteContainerPairSecondPointers(
+  gtl::STLDeleteContainerPairSecondPointers(
       available_maps_.begin(), available_maps_.end());
 }
 
diff --git a/cpp/src/phonenumbers/phonenumberutil.cc b/cpp/src/phonenumbers/phonenumberutil.cc
index f0b4e5a29..880b48826 100644
--- a/cpp/src/phonenumbers/phonenumberutil.cc
+++ b/cpp/src/phonenumbers/phonenumberutil.cc
@@ -51,6 +51,7 @@ namespace i18n {
 namespace phonenumbers {
 
 using google::protobuf::RepeatedField;
+using gtl::OrderByFirst;
 
 // static constants
 const size_t PhoneNumberUtil::kMinLengthForNsn;
@@ -808,7 +809,7 @@ PhoneNumberUtil::PhoneNumberUtil()
 }
 
 PhoneNumberUtil::~PhoneNumberUtil() {
-  STLDeleteContainerPairSecondPointers(
+  gtl::STLDeleteContainerPairSecondPointers(
       country_calling_code_to_region_code_map_->begin(),
       country_calling_code_to_region_code_map_->end());
 }
diff --git a/cpp/src/phonenumbers/stl_util.h b/cpp/src/phonenumbers/stl_util.h
index d3199ce10..77ffbbe99 100644
--- a/cpp/src/phonenumbers/stl_util.h
+++ b/cpp/src/phonenumbers/stl_util.h
@@ -18,6 +18,7 @@
 namespace i18n {
 namespace phonenumbers {
 
+namespace gtl {
 // Compares the first attribute of two pairs.
 struct OrderByFirst {
   template <typename T>
@@ -44,7 +45,7 @@ void STLDeleteElements(T* container) {
     delete *it;
   }
 }
-
+}  // namespace gtl
 }  // namespace phonenumbers
 }  // namespace i18n
 
diff --git a/cpp/test/phonenumbers/regexp_adapter_test.cc b/cpp/test/phonenumbers/regexp_adapter_test.cc
index 6376c97cd..88a930147 100644
--- a/cpp/test/phonenumbers/regexp_adapter_test.cc
+++ b/cpp/test/phonenumbers/regexp_adapter_test.cc
@@ -69,9 +69,7 @@ class RegExpAdapterTest : public testing::Test {
 #endif  // I18N_PHONENUMBERS_USE_RE2
   }
 
-  ~RegExpAdapterTest() {
-    STLDeleteElements(&contexts_);
-  }
+  ~RegExpAdapterTest() { gtl::STLDeleteElements(&contexts_); }
 
   static string ErrorMessage(const RegExpTestContext& context) {
     return StrCat("Test failed with ", context.name, " implementation.");