diff --git a/include/fmt/core.h b/include/fmt/core.h
index 900d0464..8959dac9 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -31,6 +31,16 @@
 # define FMT_MSC_VER 0
 #endif
 
+#ifndef FMT_NULL
+# if FMT_HAS_FEATURE(cxx_nullptr) || \
+   (FMT_GCC_VERSION >= 408 && FMT_HAS_GXX_CXX11) || \
+   FMT_MSC_VER >= 1600
+#  define FMT_NULL nullptr
+# else
+#  define FMT_NULL NULL
+# endif
+#endif
+
 // Check if exceptions are disabled.
 #if defined(__GNUC__) && !defined(__EXCEPTIONS)
 # define FMT_EXCEPTIONS 0
@@ -211,7 +221,7 @@ class basic_buffer {
   std::size_t capacity_;
 
  protected:
-  basic_buffer(T *p = 0, std::size_t size = 0, std::size_t capacity = 0)
+  basic_buffer(T *p = FMT_NULL, std::size_t size = 0, std::size_t capacity = 0)
     FMT_NOEXCEPT: ptr_(p), size_(size), capacity_(capacity) {}
 
   /** Sets the buffer data and capacity. */
diff --git a/include/fmt/format.cc b/include/fmt/format.cc
index 15702a0c..57f68185 100644
--- a/include/fmt/format.cc
+++ b/include/fmt/format.cc
@@ -154,7 +154,8 @@ int safe_strerror(
       : error_code_(err_code), buffer_(buf), buffer_size_(buf_size) {}
 
     int run() {
-      strerror_r(0, 0, "");  // Suppress a warning about unused strerror_r.
+      // Suppress a warning about unused strerror_r.
+      strerror_r(0, FMT_NULL, "");
       return handle(strerror_r(error_code_, buffer_, buffer_size_));
     }
   };
@@ -282,7 +283,7 @@ FMT_FUNC internal::utf8_to_utf16::utf8_to_utf16(string_view s) {
     FMT_THROW(windows_error(ERROR_INVALID_PARAMETER, ERROR_MSG));
   int s_size = static_cast<int>(s.size());
   int length = MultiByteToWideChar(
-      CP_UTF8, MB_ERR_INVALID_CHARS, s.data(), s_size, 0, 0);
+      CP_UTF8, MB_ERR_INVALID_CHARS, s.data(), s_size, FMT_NULL, 0);
   if (length == 0)
     FMT_THROW(windows_error(GetLastError(), ERROR_MSG));
   buffer_.resize(length + 1);
@@ -304,12 +305,13 @@ FMT_FUNC int internal::utf16_to_utf8::convert(wstring_view s) {
   if (s.size() > INT_MAX)
     return ERROR_INVALID_PARAMETER;
   int s_size = static_cast<int>(s.size());
-  int length = WideCharToMultiByte(CP_UTF8, 0, s.data(), s_size, 0, 0, 0, 0);
+  int length = WideCharToMultiByte(
+        CP_UTF8, 0, s.data(), s_size, FMT_NULL, 0, FMT_NULL, FMT_NULL);
   if (length == 0)
     return GetLastError();
   buffer_.resize(length + 1);
   length = WideCharToMultiByte(
-    CP_UTF8, 0, s.data(), s_size, &buffer_[0], length, 0, 0);
+    CP_UTF8, 0, s.data(), s_size, &buffer_[0], length, FMT_NULL, FMT_NULL);
   if (length == 0)
     return GetLastError();
   buffer_[length] = 0;
@@ -334,8 +336,8 @@ FMT_FUNC void internal::format_windows_error(
       wchar_t *system_message = &buf[0];
       int result = FormatMessageW(
           FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
-          0, error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-          system_message, static_cast<uint32_t>(buf.size()), 0);
+          FMT_NULL, error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+          system_message, static_cast<uint32_t>(buf.size()), FMT_NULL);
       if (result != 0) {
         utf16_to_utf8 utf8_message;
         if (utf8_message.convert(system_message) == ERROR_SUCCESS) {
diff --git a/include/fmt/format.h b/include/fmt/format.h
index b87826db..ac9af06f 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -2560,7 +2560,7 @@ void basic_writer<Range>::write_double(T value, const format_specs &spec) {
 
   // Format using snprintf.
   unsigned n = 0;
-  char_type *start = 0;
+  char_type *start = FMT_NULL;
   for (;;) {
     std::size_t buffer_size = buffer.capacity();
 #if FMT_MSC_VER
diff --git a/include/fmt/posix.cc b/include/fmt/posix.cc
index 8cc42cd2..a3c076ca 100644
--- a/include/fmt/posix.cc
+++ b/include/fmt/posix.cc
@@ -77,7 +77,7 @@ void fmt::BufferedFile::close() {
   if (!file_)
     return;
   int result = FMT_SYSTEM(fclose(file_));
-  file_ = 0;
+  file_ = FMT_NULL;
   if (result != 0)
     FMT_THROW(system_error(errno, "cannot close file"));
 }
diff --git a/include/fmt/posix.h b/include/fmt/posix.h
index 2cf838d7..42b27e92 100644
--- a/include/fmt/posix.h
+++ b/include/fmt/posix.h
@@ -156,7 +156,7 @@ public:
 
   // A "move constructor" for moving from an lvalue.
   BufferedFile(BufferedFile &f) FMT_NOEXCEPT : file_(f.file_) {
-    f.file_ = 0;
+    f.file_ = FMT_NULL;
   }
 
   // A "move assignment operator" for moving from a temporary.
@@ -170,7 +170,7 @@ public:
   BufferedFile &operator=(BufferedFile &other) {
     close();
     file_ = other.file_;
-    other.file_ = 0;
+    other.file_ = FMT_NULL;
     return *this;
   }
 
@@ -178,7 +178,7 @@ public:
   //   BufferedFile file = BufferedFile(...);
   operator Proxy() FMT_NOEXCEPT {
     Proxy p = {file_};
-    file_ = 0;
+    file_ = FMT_NULL;
     return p;
   }
 
@@ -188,13 +188,13 @@ public:
 
  public:
   BufferedFile(BufferedFile &&other) FMT_NOEXCEPT : file_(other.file_) {
-    other.file_ = 0;
+    other.file_ = FMT_NULL;
   }
 
   BufferedFile& operator=(BufferedFile &&other) {
     close();
     file_ = other.file_;
-    other.file_ = 0;
+    other.file_ = FMT_NULL;
     return *this;
   }
 #endif
@@ -386,7 +386,7 @@ class Locale {
  public:
   typedef locale_t Type;
 
-  Locale() : locale_(newlocale(LC_NUMERIC_MASK, "C", NULL)) {
+  Locale() : locale_(newlocale(LC_NUMERIC_MASK, "C", FMT_NULL)) {
     if (!locale_)
       FMT_THROW(fmt::system_error(errno, "cannot create locale"));
   }
@@ -397,7 +397,7 @@ class Locale {
   // Converts string to floating-point number and advances str past the end
   // of the parsed input.
   double strtod(const char *&str) const {
-    char *end = 0;
+    char *end = FMT_NULL;
     double result = strtod_l(str, &end, locale_);
     str = end;
     return result;
diff --git a/include/fmt/time.h b/include/fmt/time.h
index a33c0b30..08199425 100644
--- a/include/fmt/time.h
+++ b/include/fmt/time.h
@@ -33,7 +33,7 @@ inline std::tm localtime(std::time_t time) {
       return handle(localtime_r(&time_, &tm_));
     }
 
-    bool handle(std::tm* tm) { return tm != 0; }
+    bool handle(std::tm *tm) { return tm != FMT_NULL; }
 
     bool handle(internal::null<>) {
       using namespace fmt::internal;
@@ -44,9 +44,9 @@ inline std::tm localtime(std::time_t time) {
 
     bool fallback(internal::null<>) {
       using namespace fmt::internal;
-      std::tm* tm = std::localtime(&time_);
-      if (tm != 0) tm_ = *tm;
-      return tm != 0;
+      std::tm *tm = std::localtime(&time_);
+      if (tm) tm_ = *tm;
+      return tm != FMT_NULL;
     }
   };
   LocalTime lt(time);
@@ -70,7 +70,7 @@ inline std::tm gmtime(std::time_t time) {
       return handle(gmtime_r(&time_, &tm_));
     }
 
-    bool handle(std::tm* tm) { return tm != 0; }
+    bool handle(std::tm *tm) { return tm != FMT_NULL; }
 
     bool handle(internal::null<>) {
       using namespace fmt::internal;
@@ -80,9 +80,9 @@ inline std::tm gmtime(std::time_t time) {
     bool fallback(int res) { return res == 0; }
 
     bool fallback(internal::null<>) {
-      std::tm* tm = std::gmtime(&time_);
-      if (tm != 0) tm_ = *tm;
-      return tm != 0;
+      std::tm *tm = std::gmtime(&time_);
+      if (tm) tm_ = *tm;
+      return tm != FMT_NULL;
     }
   };
   GMTime gt(time);