diff --git a/webrtc/modules/audio_coding/main/acm2/call_statistics.cc b/webrtc/modules/audio_coding/main/acm2/call_statistics.cc
index 9153325af..4c3e9fc39 100644
--- a/webrtc/modules/audio_coding/main/acm2/call_statistics.cc
+++ b/webrtc/modules/audio_coding/main/acm2/call_statistics.cc
@@ -10,7 +10,7 @@
 
 #include "webrtc/modules/audio_coding/main/acm2/call_statistics.h"
 
-#include <cassert>
+#include <assert.h>
 
 namespace webrtc {
 
diff --git a/webrtc/modules/audio_coding/main/acm2/initial_delay_manager_unittest.cc b/webrtc/modules/audio_coding/main/acm2/initial_delay_manager_unittest.cc
index 1e129f37e..15e88a539 100644
--- a/webrtc/modules/audio_coding/main/acm2/initial_delay_manager_unittest.cc
+++ b/webrtc/modules/audio_coding/main/acm2/initial_delay_manager_unittest.cc
@@ -8,7 +8,7 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include <cstring>
+#include <string.h>
 
 #include "gtest/gtest.h"
 #include "webrtc/modules/audio_coding/main/acm2/initial_delay_manager.h"
diff --git a/webrtc/modules/audio_coding/neteq4/neteq_unittest.cc b/webrtc/modules/audio_coding/neteq4/neteq_unittest.cc
index b3372766b..32f5bf40b 100644
--- a/webrtc/modules/audio_coding/neteq4/neteq_unittest.cc
+++ b/webrtc/modules/audio_coding/neteq4/neteq_unittest.cc
@@ -14,10 +14,10 @@
 
 #include "webrtc/modules/audio_coding/neteq4/interface/neteq.h"
 
+#include <math.h>
 #include <stdlib.h>
 #include <string.h>  // memset
 
-#include <cmath>
 #include <set>
 #include <string>
 #include <vector>
diff --git a/webrtc/modules/desktop_capture/mouse_cursor_monitor_null.cc b/webrtc/modules/desktop_capture/mouse_cursor_monitor_null.cc
index 94a20e113..3a632cc0d 100644
--- a/webrtc/modules/desktop_capture/mouse_cursor_monitor_null.cc
+++ b/webrtc/modules/desktop_capture/mouse_cursor_monitor_null.cc
@@ -10,7 +10,7 @@
 
 #include "webrtc/modules/desktop_capture/mouse_cursor_monitor.h"
 
-#include <cstddef>
+#include <stddef.h>
 
 namespace webrtc {
 
diff --git a/webrtc/modules/desktop_capture/window_capturer_x11.cc b/webrtc/modules/desktop_capture/window_capturer_x11.cc
index 3d5179417..473231f9c 100755
--- a/webrtc/modules/desktop_capture/window_capturer_x11.cc
+++ b/webrtc/modules/desktop_capture/window_capturer_x11.cc
@@ -10,13 +10,14 @@
 
 #include "webrtc/modules/desktop_capture/window_capturer.h"
 
+#include <assert.h>
 #include <string.h>
 #include <X11/Xatom.h>
 #include <X11/extensions/Xcomposite.h>
 #include <X11/extensions/Xrender.h>
 #include <X11/Xutil.h>
+
 #include <algorithm>
-#include <cassert>
 
 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_baselinefile.cc b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_baselinefile.cc
index 30723be99..48b66a440 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_baselinefile.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_baselinefile.cc
@@ -10,8 +10,9 @@
 
 #include "webrtc/modules/remote_bitrate_estimator/test/bwe_test_baselinefile.h"
 
+#include <stdio.h>
+
 #include <algorithm>
-#include <cstdio>
 #include <vector>
 
 #include "webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.h"
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.cc b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.cc
index 4e5d4074a..0d2021ebb 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.cc
@@ -15,7 +15,7 @@
 #else
 #include <arpa/inet.h>
 #endif
-#include <cassert>
+#include <assert.h>
 
 #include "webrtc/modules/remote_bitrate_estimator/test/bwe_test_logging.h"
 #include "webrtc/system_wrappers/interface/scoped_ptr.h"
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.h b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.h
index 397a16977..dddbdeeb2 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.h
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_fileutils.h
@@ -11,7 +11,8 @@
 #ifndef WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_BWE_TEST_FILEUTILS_H_
 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_BWE_TEST_FILEUTILS_H_
 
-#include <cstdio>
+#include <stdio.h>
+
 #include <string>
 
 #include "webrtc/modules/interface/module_common_types.h"
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc
index 86506fb1b..f93b14824 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.cc
@@ -10,7 +10,8 @@
 
 #include "webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.h"
 
-#include <cstdio>
+#include <stdio.h>
+
 #include <sstream>
 
 namespace webrtc {
@@ -83,7 +84,7 @@ int Random::Gaussian(int mean, int standard_deviation) {
   a_ ^= b_;
   b_ += a_;
   return static_cast<int>(mean + standard_deviation *
-      std::sqrt(-2 * std::log(u1)) * std::cos(2 * kPi * u2));
+      sqrt(-2 * log(u1)) * cos(2 * kPi * u2));
 }
 
 Packet::Packet()
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.h b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.h
index f5bd326a6..8d2bf80a4 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.h
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.h
@@ -11,9 +11,10 @@
 #ifndef WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_BWE_TEST_FRAMEWORK_H_
 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_BWE_TEST_FRAMEWORK_H_
 
+#include <assert.h>
+#include <math.h>
+
 #include <algorithm>
-#include <cassert>
-#include <cmath>
 #include <list>
 #include <numeric>
 #include <string>
@@ -71,7 +72,7 @@ template<typename T> class Stats {
     return variance_;
   }
   T GetStdDev() {
-    return std::sqrt(static_cast<double>(GetVariance()));
+    return sqrt(static_cast<double>(GetVariance()));
   }
   T GetMin() {
     RefreshMinMax();
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework_unittest.cc b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework_unittest.cc
index 31bb27e38..274dc76e2 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework_unittest.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework_unittest.cc
@@ -41,12 +41,12 @@ TEST(BweTestFramework_RandomTest, Gaussian) {
   }
 
   const double kPi = 3.14159265358979323846;
-  const double kScale = kN / (kStddev * std::sqrt(2.0 * kPi));
+  const double kScale = kN / (kStddev * sqrt(2.0 * kPi));
   const double kDiv = -2.0 * kStddev * kStddev;
   double self_corr = 0.0;
   double bucket_corr = 0.0;
   for (int n = 0; n < kBuckets; ++n) {
-    double normal_dist = kScale * std::exp((n - kMean) * (n - kMean) / kDiv);
+    double normal_dist = kScale * exp((n - kMean) * (n - kMean) / kDiv);
     self_corr += normal_dist * normal_dist;
     bucket_corr += normal_dist * buckets[n];
   }
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_logging.cc b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_logging.cc
index 1a43f09c2..65369fde3 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe_test_logging.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe_test_logging.cc
@@ -12,9 +12,10 @@
 
 #if BWE_TEST_LOGGING_COMPILE_TIME_ENABLE
 
+#include <stdarg.h>
+#include <stdio.h>
+
 #include <algorithm>
-#include <cstdarg>
-#include <cstdio>
 
 #include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
 #include "webrtc/system_wrappers/interface/thread_wrapper.h"
diff --git a/webrtc/modules/video_coding/codecs/test/packet_manipulator.cc b/webrtc/modules/video_coding/codecs/test/packet_manipulator.cc
index 0583e9ef1..f4ca92a96 100644
--- a/webrtc/modules/video_coding/codecs/test/packet_manipulator.cc
+++ b/webrtc/modules/video_coding/codecs/test/packet_manipulator.cc
@@ -90,7 +90,7 @@ inline double PacketManipulatorImpl::RandomUniform() {
   // get the same behavior as long as we're using a fixed initial seed.
   critsect_->Enter();
   srand(random_seed_);
-  random_seed_ = std::rand();
+  random_seed_ = rand();
   critsect_->Leave();
   return (random_seed_ + 1.0)/(RAND_MAX + 1.0);
 }
diff --git a/webrtc/modules/video_coding/codecs/test_framework/test.h b/webrtc/modules/video_coding/codecs/test_framework/test.h
index 890d0cb50..7558abe6b 100644
--- a/webrtc/modules/video_coding/codecs/test_framework/test.h
+++ b/webrtc/modules/video_coding/codecs/test_framework/test.h
@@ -41,7 +41,7 @@ protected:
     virtual void Teardown();
     double ActualBitRate(int nFrames);
     virtual bool PacketLoss(double lossRate, int /*thrown*/);
-    static double RandUniform() { return (std::rand() + 1.0)/(RAND_MAX + 1.0); }
+    static double RandUniform() { return (rand() + 1.0)/(RAND_MAX + 1.0); }
     static void VideoEncodedBufferToEncodedImage(
         webrtc::VideoFrame& videoBuffer,
         webrtc::EncodedImage &image);
diff --git a/webrtc/modules/video_coding/main/test/jitter_estimate_test.h b/webrtc/modules/video_coding/main/test/jitter_estimate_test.h
index 9318a4912..dd349b2e0 100644
--- a/webrtc/modules/video_coding/main/test/jitter_estimate_test.h
+++ b/webrtc/modules/video_coding/main/test/jitter_estimate_test.h
@@ -17,7 +17,7 @@
 #include <stdlib.h>
 #include <math.h>
 
-double const pi = 4*std::atan(1.0);
+double const pi = 4 * atan(1.0);
 
 class GaussDist
 {
@@ -26,9 +26,10 @@ public:
 
     double RandValue() // returns a single normally distributed number
     {
-        double r1 = (std::rand() + 1.0)/(RAND_MAX + 1.0); // gives equal distribution in (0, 1]
-        double r2 = (std::rand() + 1.0)/(RAND_MAX + 1.0);
-        return _mu + _sigma * sqrt(-2*std::log(r1))*std::cos(2*pi*r2);
+        double r1 = (rand() + 1.0) /
+                    (RAND_MAX + 1.0);  // gives equal distribution in (0, 1]
+        double r2 = (rand() + 1.0) / (RAND_MAX + 1.0);
+        return _mu + _sigma * sqrt(-2 * log(r1)) * cos(2 * pi * r2);
     }
 
     double GetAverage()
@@ -86,7 +87,7 @@ public:
     void SetLossRate(double rate);
 
 private:
-    double RandUniform() { return (std::rand() + 1.0)/(RAND_MAX + 1.0); }
+    double RandUniform() { return (rand() + 1.0)/(RAND_MAX + 1.0); }
     unsigned int _frameRate;
     unsigned int _capacity;
     unsigned int _rate;
diff --git a/webrtc/modules/video_coding/main/test/test_callbacks.cc b/webrtc/modules/video_coding/main/test/test_callbacks.cc
index 8e9677638..710a06ea1 100644
--- a/webrtc/modules/video_coding/main/test/test_callbacks.cc
+++ b/webrtc/modules/video_coding/main/test/test_callbacks.cc
@@ -406,7 +406,7 @@ RTPSendCompleteCallback::PacketLoss()
 bool
 RTPSendCompleteCallback::UnifomLoss(double lossPct)
 {
-    double randVal = (std::rand() + 1.0)/(RAND_MAX + 1.0);
+    double randVal = (rand() + 1.0) / (RAND_MAX + 1.0);
     return randVal < lossPct/100;
 }
 
diff --git a/webrtc/system_wrappers/interface/template_util.h b/webrtc/system_wrappers/interface/template_util.h
index 5ae415b5a..410e04cc9 100644
--- a/webrtc/system_wrappers/interface/template_util.h
+++ b/webrtc/system_wrappers/interface/template_util.h
@@ -13,7 +13,7 @@
 #ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_TEMPLATE_UTIL_H_
 #define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_TEMPLATE_UTIL_H_
 
-#include <cstddef>  // For size_t.
+#include <stddef.h>  // For size_t.
 
 namespace webrtc {