diff --git a/.clang-tidy b/.clang-tidy
index 52834b2..809d8d7 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -43,7 +43,6 @@ Checks: '
     -misc-use-anonymous-namespace,
     modernize-*,
     -modernize-avoid-c-arrays,
-    -modernize-deprecated-headers,
     -modernize-loop-convert,
     -modernize-make-unique,
     -modernize-raw-string-literal,
diff --git a/src/curl.cpp b/src/curl.cpp
index 75f4824..c8ef7dc 100644
--- a/src/curl.cpp
+++ b/src/curl.cpp
@@ -18,10 +18,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+#include <cerrno>
 #include <cstdio>
 #include <cstdlib>
 #include <ctime>
-#include <errno.h>
 #include <memory>
 #include <unistd.h>
 #include <fstream>
diff --git a/src/fdcache_entity.cpp b/src/fdcache_entity.cpp
index 3ec154a..ee73d2d 100644
--- a/src/fdcache_entity.cpp
+++ b/src/fdcache_entity.cpp
@@ -18,12 +18,12 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+#include <cerrno>
 #include <cstdio>
 #include <cstdlib>
-#include <cerrno>
+#include <climits>
 #include <memory>
 #include <unistd.h>
-#include <limits.h>
 #include <sys/stat.h>
 
 #include "common.h"
diff --git a/src/fdcache_fdinfo.cpp b/src/fdcache_fdinfo.cpp
index 9886241..c104ba2 100644
--- a/src/fdcache_fdinfo.cpp
+++ b/src/fdcache_fdinfo.cpp
@@ -19,9 +19,9 @@
  */
 
 #include <algorithm>
+#include <cerrno>
 #include <cstdio>
 #include <cstdlib>
-#include <errno.h>
 #include <memory>
 #include <sys/stat.h>
 #include <unistd.h>
diff --git a/src/gnutls_auth.cpp b/src/gnutls_auth.cpp
index c0ef0dc..36d8395 100644
--- a/src/gnutls_auth.cpp
+++ b/src/gnutls_auth.cpp
@@ -18,15 +18,15 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <errno.h>
+#include <cerrno>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <pthread.h>
 #include <unistd.h>
 #include <syslog.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <string.h>
 #include <gcrypt.h>
 #include <gnutls/gnutls.h>
 #include <gnutls/crypto.h>
diff --git a/src/nss_auth.cpp b/src/nss_auth.cpp
index e58ea0f..a8fc5ca 100644
--- a/src/nss_auth.cpp
+++ b/src/nss_auth.cpp
@@ -18,15 +18,15 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <errno.h>
+#include <cerrno>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <pthread.h>
 #include <unistd.h>
 #include <syslog.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <string.h>
 #include <nss.h>
 #include <pk11pub.h>
 #include <hasht.h>
diff --git a/src/s3fs.cpp b/src/s3fs.cpp
index b5af510..64efe41 100644
--- a/src/s3fs.cpp
+++ b/src/s3fs.cpp
@@ -19,9 +19,9 @@
  */
 
 #include <algorithm>
+#include <cerrno>
 #include <cstdio>
 #include <cstdlib>
-#include <errno.h>
 #include <memory>
 #include <set>
 #include <unistd.h>
diff --git a/src/s3fs_cred.cpp b/src/s3fs_cred.cpp
index a51e0c2..bce0c95 100644
--- a/src/s3fs_cred.cpp
+++ b/src/s3fs_cred.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
-#include <errno.h>
+#include <cerrno>
 #include <unistd.h>
 #include <pwd.h>
 #include <sys/stat.h>
diff --git a/src/test_string_util.cpp b/src/test_string_util.cpp
index bdae2e6..3dcc34d 100644
--- a/src/test_string_util.cpp
+++ b/src/test_string_util.cpp
@@ -18,9 +18,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+#include <cstdint>
 #include <cstdlib>
 #include <limits>
-#include <stdint.h>
 #include <string>
 
 #include "s3fs_logger.h"
diff --git a/src/threadpoolman.cpp b/src/threadpoolman.cpp
index 3f8b6a9..a5be537 100644
--- a/src/threadpoolman.cpp
+++ b/src/threadpoolman.cpp
@@ -18,10 +18,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+#include <cerrno>
+#include <cstdint>
 #include <cstdio>
 #include <cstdlib>
-#include <errno.h>
-#include <stdint.h>
 
 #include "s3fs_logger.h"
 #include "threadpoolman.h"
diff --git a/test/cr_filename.cc b/test/cr_filename.cc
index 411d078..d0402c5 100644
--- a/test/cr_filename.cc
+++ b/test/cr_filename.cc
@@ -18,8 +18,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
-#include <stdio.h>
-#include <stdlib.h>
+#include <cstdio>
+#include <cstdlib>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
diff --git a/test/junk_data.cc b/test/junk_data.cc
index 58026bb..d1a76d0 100644
--- a/test/junk_data.cc
+++ b/test/junk_data.cc
@@ -20,9 +20,9 @@
 
 // Generate junk data at high speed.  An alternative to dd if=/dev/urandom.
 
-#include <stdio.h>
-#include <stdint.h>
-#include <stdlib.h>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
 
 int main(int argc, const char *argv[])
 {
diff --git a/test/mknod_test.cc b/test/mknod_test.cc
index 3b31edb..f206d3c 100644
--- a/test/mknod_test.cc
+++ b/test/mknod_test.cc
@@ -18,15 +18,14 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdbool.h>
+#include <cerrno>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
-#include <string.h>
-#include <errno.h>
 #ifndef __APPLE__
 #include <sys/sysmacros.h>
 #endif
diff --git a/test/truncate_read_file.cc b/test/truncate_read_file.cc
index eb9697d..9228a15 100644
--- a/test/truncate_read_file.cc
+++ b/test/truncate_read_file.cc
@@ -18,8 +18,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
-#include <stdio.h>
-#include <stdlib.h>
+#include <cstdio>
+#include <cstdlib>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
diff --git a/test/write_multiblock.cc b/test/write_multiblock.cc
index a6e4300..e77f98f 100644
--- a/test/write_multiblock.cc
+++ b/test/write_multiblock.cc
@@ -18,8 +18,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+#include <cerrno>
 #include <cstdio>
 #include <cstdlib>
+#include <cstring>
 #include <iostream>
 #include <climits>
 #include <list>
@@ -31,8 +33,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
-#include <string.h>
-#include <errno.h>
 
 //---------------------------------------------------------
 // Structures and Typedefs