diff --git a/projects/demo/Md2Skini.cpp b/projects/demo/Md2Skini.cpp
index 5062685..3cc8ab6 100644
--- a/projects/demo/Md2Skini.cpp
+++ b/projects/demo/Md2Skini.cpp
@@ -13,7 +13,9 @@
 #include "RtMidi.h"
 #include "SKINI.msg"
 #include <iostream>
-#include <stdlib.h>
+#include <cstdlib>
+#include <cstring>
+#include <cstdio>
 
 void usage(void) {
   std::cout << "\nuseage: Md2Skini <flag(s)>\n\n";
@@ -28,7 +30,7 @@ void usage(void) {
   exit(0);
 }
 
-#include <signal.h>
+#include <csignal>
 static void finish( int ignore ){ std::cout << "Type 'Exit' to quit." << std::endl; }
 bool parseSkiniControl = true;
 
diff --git a/projects/demo/demo.cpp b/projects/demo/demo.cpp
index 6eb37e1..c82f506 100644
--- a/projects/demo/demo.cpp
+++ b/projects/demo/demo.cpp
@@ -19,7 +19,7 @@
 // functions are defined in utilites.cpp ... specific to this program.
 #include "utilities.h"
 
-#include <signal.h>
+#include <csignal>
 #include <iostream>
 #include <algorithm>
 #include <cmath>
diff --git a/projects/demo/utilities.cpp b/projects/demo/utilities.cpp
index 65b6a0b..0823ad7 100644
--- a/projects/demo/utilities.cpp
+++ b/projects/demo/utilities.cpp
@@ -2,8 +2,8 @@
 //
 // Gary P. Scavone, 1999.
 
-#include <stdlib.h>
-#include <string.h>
+#include <cstdlib>
+#include <cstring>
 #include "utilities.h"
 
 // STK Instrument Classes
diff --git a/projects/effects/effects.cpp b/projects/effects/effects.cpp
index 616bd64..5771af8 100644
--- a/projects/effects/effects.cpp
+++ b/projects/effects/effects.cpp
@@ -13,7 +13,7 @@
 #include "Messager.h"
 #include "RtAudio.h"
 
-#include <signal.h>
+#include <csignal>
 #include <cstring>
 #include <iostream>
 #include <algorithm>
diff --git a/projects/examples/controlbee.cpp b/projects/examples/controlbee.cpp
index f2ba4b1..e287ea7 100644
--- a/projects/examples/controlbee.cpp
+++ b/projects/examples/controlbee.cpp
@@ -4,7 +4,7 @@
 #include "RtAudio.h"
 #include "Messager.h"
 #include "SKINI.msg"
-#include <math.h>
+#include <cmath>
 #include <algorithm>
 using std::min;
 
diff --git a/projects/examples/play.cpp b/projects/examples/play.cpp
index 98f3312..6af7777 100644
--- a/projects/examples/play.cpp
+++ b/projects/examples/play.cpp
@@ -16,7 +16,7 @@
 #include "FileWvIn.h"
 #include "RtAudio.h"
 
-#include <signal.h>
+#include <csignal>
 #include <iostream>
 #include <cstdlib>
 
diff --git a/projects/examples/playsmf.cpp b/projects/examples/playsmf.cpp
index 94702ba..5ee4360 100644
--- a/projects/examples/playsmf.cpp
+++ b/projects/examples/playsmf.cpp
@@ -7,7 +7,7 @@
 
 #include "MidiFileIn.h"
 #include "RtMidi.h"
-#include <signal.h>
+#include <csignal>
 #include <cstdlib>
 
 bool done = false;
diff --git a/projects/ragamatic/ragamat.cpp b/projects/ragamatic/ragamat.cpp
index 5f3174f..ff5bc8e 100644
--- a/projects/ragamatic/ragamat.cpp
+++ b/projects/ragamatic/ragamat.cpp
@@ -10,7 +10,7 @@
 #include "Messager.h"
 #include "RtAudio.h"
 
-#include <signal.h>
+#include <csignal>
 #include <cstring>
 #include <iostream>
 #include <algorithm>
diff --git a/src/Messager.cpp b/src/Messager.cpp
index 2136094..3f89b7e 100644
--- a/src/Messager.cpp
+++ b/src/Messager.cpp
@@ -302,7 +302,7 @@ bool Messager :: startSocketInput( int port )
 
 #if (defined(__OS_IRIX__) || defined(__OS_LINUX__) || defined(__OS_MACOSX__))
   #include <sys/time.h>
-  #include <errno.h>
+  #include <cerrno>
 #endif
 
 THREAD_RETURN THREAD_TYPE socketHandler(void *ptr)
diff --git a/src/Noise.cpp b/src/Noise.cpp
index 063487e..01244ae 100644
--- a/src/Noise.cpp
+++ b/src/Noise.cpp
@@ -11,7 +11,7 @@
 /***************************************************/
 
 #include "Noise.h"
-#include <time.h>
+#include <ctime>
 
 namespace stk {
 
diff --git a/src/RtAudio.cpp b/src/RtAudio.cpp
index 78259e9..fb190ba 100644
--- a/src/RtAudio.cpp
+++ b/src/RtAudio.cpp
@@ -45,6 +45,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <climits>
+#include <cstdio>
 
 // Static variable definitions.
 const unsigned int RtApi::MAX_SAMPLE_RATES = 14;
@@ -6299,11 +6300,10 @@ extern "C" void *alsaCallbackHandler( void *ptr )
 
 #include <unistd.h>
 #include <sys/ioctl.h>
-#include <unistd.h>
 #include <fcntl.h>
 #include "soundcard.h"
-#include <errno.h>
-#include <math.h>
+#include <cerrno>
+#include <cmath>
 
 extern "C" void *ossCallbackHandler(void * ptr);
 
diff --git a/src/Stk.cpp b/src/Stk.cpp
index 1a6f740..f41aa08 100644
--- a/src/Stk.cpp
+++ b/src/Stk.cpp
@@ -51,6 +51,7 @@
 /***************************************************/
 
 #include "Stk.h"
+#include <cstdlib>
 
 namespace stk {