diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index acc47b9c76..9d05c0f795 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -3344,7 +3344,7 @@ THREADED_TEST(ConversionException) {
   CheckUncle(&try_catch);
 
   double number_value = obj->NumberValue();
-  CHECK_NE(0, isnan(number_value));
+  CHECK_NE(0, std::isnan(number_value));
   CheckUncle(&try_catch);
 
   int64_t integer_value = obj->IntegerValue();
@@ -15445,7 +15445,7 @@ static uint64_t DoubleToBits(double value) {
 
 static double DoubleToDateTime(double input) {
   double date_limit = 864e13;
-  if (isnan(input) || input < -date_limit || input > date_limit) {
+  if (std::isnan(input) || input < -date_limit || input > date_limit) {
     return i::OS::nan_value();
   }
   return (input < 0) ? -(floor(-input)) : floor(input);
@@ -15506,7 +15506,7 @@ THREADED_TEST(QuietSignalingNaNs) {
     // Check that Number::New preserves non-NaNs and quiets SNaNs.
     v8::Handle<v8::Value> number = v8::Number::New(test_value);
     double stored_number = number->NumberValue();
-    if (!isnan(test_value)) {
+    if (!std::isnan(test_value)) {
       CHECK_EQ(test_value, stored_number);
     } else {
       uint64_t stored_bits = DoubleToBits(stored_number);
@@ -15525,7 +15525,7 @@ THREADED_TEST(QuietSignalingNaNs) {
     v8::Handle<v8::Value> date = v8::Date::New(test_value);
     double expected_stored_date = DoubleToDateTime(test_value);
     double stored_date = date->NumberValue();
-    if (!isnan(expected_stored_date)) {
+    if (!std::isnan(expected_stored_date)) {
       CHECK_EQ(expected_stored_date, stored_date);
     } else {
       uint64_t stored_bits = DoubleToBits(stored_date);
diff --git a/test/cctest/test-conversions.cc b/test/cctest/test-conversions.cc
index 4815b1b6d3..651dc59d58 100644
--- a/test/cctest/test-conversions.cc
+++ b/test/cctest/test-conversions.cc
@@ -81,10 +81,10 @@ TEST(MalformedOctal) {
   CHECK_EQ(81.0, StringToDouble(&uc, "081", ALLOW_HEX | ALLOW_OCTALS));
   CHECK_EQ(78.0, StringToDouble(&uc, "078", ALLOW_HEX | ALLOW_OCTALS));
 
-  CHECK(isnan(StringToDouble(&uc, "07.7", ALLOW_HEX | ALLOW_OCTALS)));
-  CHECK(isnan(StringToDouble(&uc, "07.8", ALLOW_HEX | ALLOW_OCTALS)));
-  CHECK(isnan(StringToDouble(&uc, "07e8", ALLOW_HEX | ALLOW_OCTALS)));
-  CHECK(isnan(StringToDouble(&uc, "07e7", ALLOW_HEX | ALLOW_OCTALS)));
+  CHECK(std::isnan(StringToDouble(&uc, "07.7", ALLOW_HEX | ALLOW_OCTALS)));
+  CHECK(std::isnan(StringToDouble(&uc, "07.8", ALLOW_HEX | ALLOW_OCTALS)));
+  CHECK(std::isnan(StringToDouble(&uc, "07e8", ALLOW_HEX | ALLOW_OCTALS)));
+  CHECK(std::isnan(StringToDouble(&uc, "07e7", ALLOW_HEX | ALLOW_OCTALS)));
 
   CHECK_EQ(8.7, StringToDouble(&uc, "08.7", ALLOW_HEX | ALLOW_OCTALS));
   CHECK_EQ(8e7, StringToDouble(&uc, "08e7", ALLOW_HEX | ALLOW_OCTALS));
@@ -123,9 +123,9 @@ TEST(TrailingJunk) {
 
 TEST(NonStrDecimalLiteral) {
   UnicodeCache uc;
-  CHECK(isnan(StringToDouble(&uc, " ", NO_FLAGS, OS::nan_value())));
-  CHECK(isnan(StringToDouble(&uc, "", NO_FLAGS, OS::nan_value())));
-  CHECK(isnan(StringToDouble(&uc, " ", NO_FLAGS, OS::nan_value())));
+  CHECK(std::isnan(StringToDouble(&uc, " ", NO_FLAGS, OS::nan_value())));
+  CHECK(std::isnan(StringToDouble(&uc, "", NO_FLAGS, OS::nan_value())));
+  CHECK(std::isnan(StringToDouble(&uc, " ", NO_FLAGS, OS::nan_value())));
   CHECK_EQ(0.0, StringToDouble(&uc, "", NO_FLAGS));
   CHECK_EQ(0.0, StringToDouble(&uc, " ", NO_FLAGS));
 }
@@ -140,8 +140,8 @@ TEST(IntegerStrLiteral) {
   CHECK_EQ(-1.0, StringToDouble(&uc, "-1", NO_FLAGS));
   CHECK_EQ(-1.0, StringToDouble(&uc, "  -1  ", NO_FLAGS));
   CHECK_EQ(1.0, StringToDouble(&uc, "  +1  ", NO_FLAGS));
-  CHECK(isnan(StringToDouble(&uc, "  -  1  ", NO_FLAGS)));
-  CHECK(isnan(StringToDouble(&uc, "  +  1  ", NO_FLAGS)));
+  CHECK(std::isnan(StringToDouble(&uc, "  -  1  ", NO_FLAGS)));
+  CHECK(std::isnan(StringToDouble(&uc, "  +  1  ", NO_FLAGS)));
 
   CHECK_EQ(0.0, StringToDouble(&uc, "0e0", ALLOW_HEX | ALLOW_OCTALS));
   CHECK_EQ(0.0, StringToDouble(&uc, "0e1", ALLOW_HEX | ALLOW_OCTALS));
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index 9aa839be6c..c0bd08af16 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -199,7 +199,7 @@ TEST(HeapObjects) {
 
   // nan oddball checks
   CHECK(heap->nan_value()->IsNumber());
-  CHECK(isnan(heap->nan_value()->Number()));
+  CHECK(std::isnan(heap->nan_value()->Number()));
 
   Handle<String> s = FACTORY->NewStringFromAscii(CStrVector("fisk hest "));
   CHECK(s->IsString());
diff --git a/test/cctest/test-log.cc b/test/cctest/test-log.cc
index 24e5db9338..89b11c9d86 100644
--- a/test/cctest/test-log.cc
+++ b/test/cctest/test-log.cc
@@ -28,10 +28,10 @@
 // Tests of logging functions from log.h
 
 #ifdef __linux__
-#include <math.h>
 #include <pthread.h>
 #include <signal.h>
 #include <unistd.h>
+#include <cmath>
 #endif  // __linux__
 
 #include "v8.h"