diff --git a/src/utilities.h b/src/utilities.h
index ca21cfb..760c142 100644
--- a/src/utilities.h
+++ b/src/utilities.h
@@ -34,26 +34,6 @@
 #ifndef UTILITIES_H__
 #define UTILITIES_H__
 
-#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
-# define OS_WINDOWS
-#elif defined(__CYGWIN__) || defined(__CYGWIN32__)
-# define OS_CYGWIN
-#elif defined(linux) || defined(__linux) || defined(__linux__)
-# ifndef OS_LINUX
-#  define OS_LINUX
-# endif
-#elif defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__)
-# define OS_MACOSX
-#elif defined(__FreeBSD__)
-# define OS_FREEBSD
-#elif defined(__NetBSD__)
-# define OS_NETBSD
-#elif defined(__OpenBSD__)
-# define OS_OPENBSD
-#else
-// TODO(hamaji): Add other platforms.
-#endif
-
 // printf macros for size_t, in the style of inttypes.h
 #ifdef _LP64
 #define __PRIS_PREFIX "z"
@@ -76,12 +56,13 @@
 
 #include <string>
 
-#if defined(OS_WINDOWS)
+#include <glog/logging.h>
+
+#if defined(GLOG_OS_WINDOWS)
 # include "port.h"
 #endif
 
 #include "config.h"
-#include "glog/logging.h"
 
 // There are three different ways we can try to get the stack trace:
 //
@@ -107,19 +88,19 @@
 
 #if defined(HAVE_LIB_UNWIND)
 # define STACKTRACE_H "stacktrace_libunwind-inl.h"
+#elif defined(HAVE__UNWIND_BACKTRACE) && defined(HAVE__UNWIND_GETIP)
+# define STACKTRACE_H "stacktrace_unwind-inl.h"
 #elif !defined(NO_FRAME_POINTER)
 # if defined(__i386__) && __GNUC__ >= 2
 #  define STACKTRACE_H "stacktrace_x86-inl.h"
-# elif defined(__x86_64__) && __GNUC__ >= 2 && HAVE_UNWIND_H
-#  define STACKTRACE_H "stacktrace_x86_64-inl.h"
 # elif (defined(__ppc__) || defined(__PPC__)) && __GNUC__ >= 2
 #  define STACKTRACE_H "stacktrace_powerpc-inl.h"
-# elif defined(OS_WINDOWS)
+# elif defined(GLOG_OS_WINDOWS)
 #  define STACKTRACE_H "stacktrace_windows-inl.h"
 # endif
 #endif
 
-#if !defined(STACKTRACE_H) && defined(HAVE_EXECINFO_H)
+#if !defined(STACKTRACE_H) && defined(HAVE_EXECINFO_BACKTRACE)
 # define STACKTRACE_H "stacktrace_generic-inl.h"
 #endif
 
@@ -127,18 +108,20 @@
 # define HAVE_STACKTRACE
 #endif
 
+#ifndef GLOG_NO_SYMBOLIZE_DETECTION
 #ifndef HAVE_SYMBOLIZE
 // defined by gcc
-#if defined(__ELF__) && defined(OS_LINUX)
+#if defined(__ELF__) && defined(GLOG_OS_LINUX)
 # define HAVE_SYMBOLIZE
-#elif defined(OS_MACOSX) && defined(HAVE_DLADDR)
+#elif defined(GLOG_OS_MACOSX) && defined(HAVE_DLADDR)
 // Use dladdr to symbolize.
 # define HAVE_SYMBOLIZE
-#elif defined(OS_WINDOWS)
+#elif defined(GLOG_OS_WINDOWS)
 // Use DbgHelp to symbolize
 # define HAVE_SYMBOLIZE
 #endif
 #endif // !defined(HAVE_SYMBOLIZE)
+#endif // !defined(GLOG_NO_SYMBOLIZE_DETECTION)
 
 #ifndef ARRAYSIZE
 // There is a better way, but this is good enough for our purpose.
@@ -152,7 +135,7 @@
 #ifdef HAVE___ATTRIBUTE__
 # define ATTRIBUTE_NOINLINE __attribute__ ((noinline))
 # define HAVE_ATTRIBUTE_NOINLINE
-#elif defined(OS_WINDOWS)
+#elif defined(GLOG_OS_WINDOWS)
 # define ATTRIBUTE_NOINLINE __declspec(noinline)
 # define HAVE_ATTRIBUTE_NOINLINE
 #else
@@ -161,15 +144,9 @@
 
 const char* ProgramInvocationShortName();
 
-bool IsGoogleLoggingInitialized();
-
-bool is_default_thread();
-
 int64 CycleClock_Now();
 
 int64 UsecToCycles(int64 usec);
-
-typedef double WallTime;
 WallTime WallTime_Now();
 
 int32 GetMainThreadPid();