diff --git a/cpp/CMakeLists.txt b/cpp/CMakeLists.txt
index d9bac861c..ba3fa9026 100644
--- a/cpp/CMakeLists.txt
+++ b/cpp/CMakeLists.txt
@@ -67,6 +67,7 @@ endfunction (find_required_program)
 # Options that can be passed to CMake using 'cmake -DKEY=VALUE'.
 option ("USE_LITE_METADATA" "Use lite metadata" "OFF")
 option ("USE_RE2" "Use RE2 instead of ICU" "OFF")
+option ("USE_STD_MAP" "Force the use of std::map" "OFF")
 
 # Find all the required libraries and programs.
 find_package (Boost 1.40.0 COMPONENTS thread)
@@ -109,17 +110,11 @@ if (APPLE)
   FIND_LIBRARY (FOUNDATION_LIB Foundation)
 endif ()
 
-INCLUDE (CheckIncludeFileCXX)
-CHECK_INCLUDE_FILE_CXX ("tr1/unordered_map" HAVE_CXX_TR1_UNORDERED_MAP)
-
-if (HAVE_CXX_TR1_UNORDERED_MAP)
-  add_definitions ("-DUSE_TR1_UNORDERED_MAP")
-else ()
-  CHECK_INCLUDE_FILE_CXX (hash_map HAVE_CXX_HASH_MAP)
-  if (HAVE_CXX_HASH_MAP)
-    add_definitions ("-DUSE_HASH_MAP")
-  else ()
-    print_error ("C++ map class" "tr1/unordered_map or hash_map")
+if (${USE_STD_MAP} STREQUAL "OFF")
+  INCLUDE (CheckIncludeFileCXX)
+  CHECK_INCLUDE_FILE_CXX ("tr1/unordered_map" HAVE_CXX_TR1_UNORDERED_MAP)
+  if (HAVE_CXX_TR1_UNORDERED_MAP)
+    add_definitions ("-DUSE_TR1_UNORDERED_MAP")
   endif ()
 endif ()
 
diff --git a/cpp/src/phonenumbers/regexp_cache.cc b/cpp/src/phonenumbers/regexp_cache.cc
index 1f130c769..7a0c9e3ac 100644
--- a/cpp/src/phonenumbers/regexp_cache.cc
+++ b/cpp/src/phonenumbers/regexp_cache.cc
@@ -26,35 +26,18 @@
 
 using std::string;
 
-#ifdef USE_HASH_MAP
-
-// A basic text book string hash function implementation, this one taken from
-// The Practice of Programming (Kernighan and Pike 1999). It could be a good
-// idea in the future to evaluate how well it actually performs and possibly
-// switch to another hash function better suited to this particular use case.
-namespace __gnu_cxx {
-template<> struct hash<string> {
-  enum { MULTIPLIER = 31 };
-  size_t operator()(const string& key) const {
-    size_t h = 0;
-    for (const char* p = key.c_str(); *p != '\0'; ++p) {
-      h *= MULTIPLIER;
-      h += *p;
-    }
-    return h;
-  }
-};
-}  // namespace __gnu_cxx
-
-#endif
-
 namespace i18n {
 namespace phonenumbers {
 
 using base::AutoLock;
 
 RegExpCache::RegExpCache(size_t min_items)
-    : cache_impl_(new CacheImpl(min_items)) {}
+#ifdef USE_TR1_UNORDERED_MAP
+    : cache_impl_(new CacheImpl(min_items))
+#else
+    : cache_impl_(new CacheImpl())
+#endif
+{}
 
 RegExpCache::~RegExpCache() {
   AutoLock l(lock_);
diff --git a/cpp/src/phonenumbers/regexp_cache.h b/cpp/src/phonenumbers/regexp_cache.h
index 7670824f7..08e19127d 100644
--- a/cpp/src/phonenumbers/regexp_cache.h
+++ b/cpp/src/phonenumbers/regexp_cache.h
@@ -36,13 +36,8 @@
 
 #ifdef USE_TR1_UNORDERED_MAP
 #  include <tr1/unordered_map>
-#elif defined(USE_HASH_MAP)
-#  ifndef __DEPRECATED
-#    define __DEPRECATED
-#  endif
-#  include <hash_map>
 #else
-#  error STL map type unsupported on this platform!
+#  include <map>
 #endif
 
 namespace i18n {
@@ -56,8 +51,8 @@ class RegExpCache {
  private:
 #ifdef USE_TR1_UNORDERED_MAP
   typedef std::tr1::unordered_map<string, const RegExp*> CacheImpl;
-#elif defined(USE_HASH_MAP)
-  typedef std::hash_map<string, const RegExp*> CacheImpl;
+#else
+  typedef std::map<string, const RegExp*> CacheImpl;
 #endif
 
  public: