diff --git a/gtk2_ardour/editor_selection.cc b/gtk2_ardour/editor_selection.cc
index b26958cd91..8a1220cdcd 100644
--- a/gtk2_ardour/editor_selection.cc
+++ b/gtk2_ardour/editor_selection.cc
@@ -18,7 +18,7 @@
 */
 
 #include <algorithm>
-#include <stdlib.h>
+#include <cstdlib>
 
 #include <pbd/stacktrace.h>
 
diff --git a/gtk2_ardour/panner2d.cc b/gtk2_ardour/panner2d.cc
index a1f99c40d4..6fa64be8e6 100644
--- a/gtk2_ardour/panner2d.cc
+++ b/gtk2_ardour/panner2d.cc
@@ -19,7 +19,7 @@
 
 #include <cmath>
 #include <climits>
-#include <string.h>
+#include <cstring>
 
 #include <gtkmm/menu.h>
 #include <gtkmm/checkmenuitem.h>
diff --git a/libs/ardour/plugin_manager.cc b/libs/ardour/plugin_manager.cc
index 5f0b9da343..6dac06f870 100644
--- a/libs/ardour/plugin_manager.cc
+++ b/libs/ardour/plugin_manager.cc
@@ -27,7 +27,7 @@
 #ifdef VST_SUPPORT
 #include <fst.h>
 #include <pbd/basename.h>
-#include <string.h>
+#include <cstring>
 #endif // VST_SUPPORT
 
 #include <glibmm/miscutils.h>
diff --git a/libs/ardour/vst_plugin.cc b/libs/ardour/vst_plugin.cc
index a23ef0e2c4..c30af3b3dc 100644
--- a/libs/ardour/vst_plugin.cc
+++ b/libs/ardour/vst_plugin.cc
@@ -20,13 +20,13 @@
 #include <algorithm>
 #include <vector>
 #include <string>
-#include <ctype.h>
+#include <cctype>
 
 #include <cstdlib>
 #include <cstdio> // so libraptor doesn't complain
 #include <cmath>
 #include <dirent.h>
-#include <string.h> // for memmove
+#include <cstring> // for memmove
 #include <sys/stat.h>
 #include <cerrno>
 
diff --git a/libs/gtkmm2ext/fastmeter.cc b/libs/gtkmm2ext/fastmeter.cc
index 2a2accccbc..f13236271d 100644
--- a/libs/gtkmm2ext/fastmeter.cc
+++ b/libs/gtkmm2ext/fastmeter.cc
@@ -25,7 +25,7 @@
 #include <gtkmm2ext/fastmeter.h>
 #include <gtkmm2ext/utils.h>
 #include <gtkmm/style.h>
-#include <string.h>
+#include <cstring>
 
 #define UINT_TO_RGB(u,r,g,b) { (*(r)) = ((u)>>16)&0xff; (*(g)) = ((u)>>8)&0xff; (*(b)) = (u)&0xff; }
 #define UINT_TO_RGBA(u,r,g,b,a) { UINT_TO_RGB(((u)>>8),r,g,b); (*(a)) = (u)&0xff; }
diff --git a/libs/pbd/base_ui.cc b/libs/pbd/base_ui.cc
index ab7495cb7b..eaf92bb555 100644
--- a/libs/pbd/base_ui.cc
+++ b/libs/pbd/base_ui.cc
@@ -20,8 +20,8 @@
 #include <stdint.h>
 #include <unistd.h>
 #include <fcntl.h>
-#include <errno.h>
-#include <string.h>
+#include <cerrno>
+#include <cstring>
 
 #include <pbd/base_ui.h>
 #include <pbd/error.h>
diff --git a/libs/pbd/enumwriter.cc b/libs/pbd/enumwriter.cc
index 7674410ec9..7033e5f3b1 100644
--- a/libs/pbd/enumwriter.cc
+++ b/libs/pbd/enumwriter.cc
@@ -18,10 +18,10 @@
     $Id$
 */
 
-#include <ctype.h>
+#include <cctype>
 
-#include <string.h>
-#include <stdlib.h>
+#include <cstring>
+#include <cstdlib>
 
 #include <pbd/enumwriter.h>
 #include <pbd/error.h>
diff --git a/libs/pbd/fpu.cc b/libs/pbd/fpu.cc
index d1c30cd753..ffb88714f6 100644
--- a/libs/pbd/fpu.cc
+++ b/libs/pbd/fpu.cc
@@ -1,5 +1,5 @@
 #define _XOPEN_SOURCE 600
-#include <stdlib.h>
+#include <cstdlib>
 #include <stdint.h>
 
 #include <pbd/fpu.h>
diff --git a/libs/pbd/stacktrace.cc b/libs/pbd/stacktrace.cc
index 375fc1eecd..1d7190fcbf 100644
--- a/libs/pbd/stacktrace.cc
+++ b/libs/pbd/stacktrace.cc
@@ -25,7 +25,7 @@
 #ifdef HAVE_EXECINFO
 
 #include <execinfo.h>
-#include <stdlib.h>
+#include <cstdlib>
 
 void
 PBD::stacktrace (std::ostream& out, int levels)
diff --git a/libs/rubberband/src/sysutils.cpp b/libs/rubberband/src/sysutils.cpp
index 120b936729..d52eee9511 100644
--- a/libs/rubberband/src/sysutils.cpp
+++ b/libs/rubberband/src/sysutils.cpp
@@ -20,14 +20,13 @@
 #ifdef __APPLE__
 #include <sys/sysctl.h>
 #else /* !__APPLE__, !_WIN32 */
-#include <stdio.h>
-#include <string.h>
+#include <cstdio>
+#include <cstring>
 #endif /* !__APPLE__, !_WIN32 */
 #endif /* !_WIN32 */
 
 #include <cstdlib>
 #include <iostream>
-#include <stdlib.h>
 
 namespace RubberBand {
 
diff --git a/libs/soundtouch/AAFilter.cpp b/libs/soundtouch/AAFilter.cpp
index d135218c54..d77c19d864 100644
--- a/libs/soundtouch/AAFilter.cpp
+++ b/libs/soundtouch/AAFilter.cpp
@@ -41,9 +41,9 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 #include <memory.h>
-#include <assert.h>
-#include <math.h>
-#include <stdlib.h>
+#include <cassert>
+#include <cmath>
+#include <cstdlib>
 #include "AAFilter.h"
 #include "FIRFilter.h"
 
diff --git a/libs/soundtouch/FIFOSampleBuffer.cpp b/libs/soundtouch/FIFOSampleBuffer.cpp
index f158ee7949..613d8f9c48 100644
--- a/libs/soundtouch/FIFOSampleBuffer.cpp
+++ b/libs/soundtouch/FIFOSampleBuffer.cpp
@@ -43,10 +43,10 @@
 //
 ////////////////////////////////////////////////////////////////////////////////
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <memory.h>
-#include <string.h>
-#include <assert.h>
+#include <cstring>
+#include <cassert>
 #include <stdexcept>
 
 #include "FIFOSampleBuffer.h"
diff --git a/libs/soundtouch/FIFOSamplePipe.h b/libs/soundtouch/FIFOSamplePipe.h
index d2d54d5274..bf42895c26 100644
--- a/libs/soundtouch/FIFOSamplePipe.h
+++ b/libs/soundtouch/FIFOSamplePipe.h
@@ -48,8 +48,8 @@
 #ifndef FIFOSamplePipe_H
 #define FIFOSamplePipe_H
 
-#include <assert.h>
-#include <stdlib.h>
+#include <cassert>
+#include <cstdlib>
 #include "STTypes.h"
 
 namespace soundtouch
diff --git a/libs/soundtouch/FIRFilter.cpp b/libs/soundtouch/FIRFilter.cpp
index cc9c40d883..1723195733 100644
--- a/libs/soundtouch/FIRFilter.cpp
+++ b/libs/soundtouch/FIRFilter.cpp
@@ -40,9 +40,9 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 #include <memory.h>
-#include <assert.h>
-#include <math.h>
-#include <stdlib.h>
+#include <cassert>
+#include <cmath>
+#include <cstdlib>
 #include <stdexcept>
 #include "FIRFilter.h"
 #include "cpu_detect.h"
diff --git a/libs/soundtouch/RateTransposer.cpp b/libs/soundtouch/RateTransposer.cpp
index 493d5326f2..3000e37e4a 100644
--- a/libs/soundtouch/RateTransposer.cpp
+++ b/libs/soundtouch/RateTransposer.cpp
@@ -39,10 +39,10 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 #include <memory.h>
-#include <assert.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <limits.h>
+#include <cassert>
+#include <cstdlib>
+#include <cstdio>
+#include <climits>
 #include "RateTransposer.h"
 #include "AAFilter.h"
 
diff --git a/libs/soundtouch/TDStretch.cpp b/libs/soundtouch/TDStretch.cpp
index c71c65967f..d08dbc2028 100644
--- a/libs/soundtouch/TDStretch.cpp
+++ b/libs/soundtouch/TDStretch.cpp
@@ -41,12 +41,12 @@
 //
 ////////////////////////////////////////////////////////////////////////////////
 
-#include <string.h>
-#include <stdlib.h>
+#include <cstring>
+#include <cstdlib>
 #include <memory.h>
-#include <limits.h>
-#include <math.h>
-#include <assert.h>
+#include <climits>
+#include <cmath>
+#include <cassert>
 
 #include "STTypes.h"
 #include "cpu_detect.h"
diff --git a/libs/surfaces/powermate/powermate.cc b/libs/surfaces/powermate/powermate.cc
index cf3aec7cfd..fde12d8d81 100644
--- a/libs/surfaces/powermate/powermate.cc
+++ b/libs/surfaces/powermate/powermate.cc
@@ -6,9 +6,9 @@
 
 
 #include <linux/input.h>
-#include <string.h>
-#include <errno.h>
-#include <stdio.h>
+#include <cstring>
+#include <cerrno>
+#include <cstdio>
 #include <unistd.h>
 #include <fcntl.h>