diff --git a/double-conversion/double-to-string.cc b/double-conversion/double-to-string.cc
index 9255bce1..bb369fe8 100644
--- a/double-conversion/double-to-string.cc
+++ b/double-conversion/double-to-string.cc
@@ -56,7 +56,7 @@ bool DoubleToStringConverter::HandleSpecialValues(
     StringBuilder* result_builder) const {
   Double double_inspect(value);
   if (double_inspect.IsInfinite()) {
-    if (infinity_symbol_ == NULL) return false;
+    if (infinity_symbol_ == DOUBLE_CONVERSION_NULLPTR) return false;
     if (value < 0) {
       result_builder->AddCharacter('-');
     }
@@ -64,7 +64,7 @@ bool DoubleToStringConverter::HandleSpecialValues(
     return true;
   }
   if (double_inspect.IsNan()) {
-    if (nan_symbol_ == NULL) return false;
+    if (nan_symbol_ == DOUBLE_CONVERSION_NULLPTR) return false;
     result_builder->AddString(nan_symbol_);
     return true;
   }
diff --git a/double-conversion/string-to-double.cc b/double-conversion/string-to-double.cc
index fe633aac..972956ca 100644
--- a/double-conversion/string-to-double.cc
+++ b/double-conversion/string-to-double.cc
@@ -474,7 +474,7 @@ double StringToDoubleConverter::StringToIeee(
     current = next_non_space;
   }
 
-  if (infinity_symbol_ != NULL) {
+  if (infinity_symbol_ != DOUBLE_CONVERSION_NULLPTR) {
     if (ConsumeFirstCharacter(*current, infinity_symbol_, allow_case_insensitivity)) {
       if (!ConsumeSubString(&current, end, infinity_symbol_, allow_case_insensitivity)) {
         return junk_string_value_;
@@ -492,7 +492,7 @@ double StringToDoubleConverter::StringToIeee(
     }
   }
 
-  if (nan_symbol_ != NULL) {
+  if (nan_symbol_ != DOUBLE_CONVERSION_NULLPTR) {
     if (ConsumeFirstCharacter(*current, nan_symbol_, allow_case_insensitivity)) {
       if (!ConsumeSubString(&current, end, nan_symbol_, allow_case_insensitivity)) {
         return junk_string_value_;
diff --git a/double-conversion/utils.h b/double-conversion/utils.h
index 868770d2..4f4dd71b 100644
--- a/double-conversion/utils.h
+++ b/double-conversion/utils.h
@@ -34,6 +34,13 @@
 #include <cstdlib>
 #include <cstring>
 
+// For pre-C++11 compatibility
+#if __cplusplus >= 201103L
+#define DOUBLE_CONVERSION_NULLPTR nullptr
+#else
+#define DOUBLE_CONVERSION_NULLPTR NULL
+#endif
+
 #include <cassert>
 #ifndef DOUBLE_CONVERSION_ASSERT
 #define DOUBLE_CONVERSION_ASSERT(condition)         \
@@ -241,9 +248,9 @@ inline int StrLength(const char* string) {
 template <typename T>
 class Vector {
  public:
-  Vector() : start_(NULL), length_(0) {}
+  Vector() : start_(DOUBLE_CONVERSION_NULLPTR), length_(0) {}
   Vector(T* data, int len) : start_(data), length_(len) {
-    DOUBLE_CONVERSION_ASSERT(len == 0 || (len > 0 && data != NULL));
+    DOUBLE_CONVERSION_ASSERT(len == 0 || (len > 0 && data != DOUBLE_CONVERSION_NULLPTR));
   }
 
   // Returns a vector using the same backing storage as this one,