diff --git a/lm/bhiksha.hh b/lm/bhiksha.hh
index 134beb2f8..8ec8989c7 100644
--- a/lm/bhiksha.hh
+++ b/lm/bhiksha.hh
@@ -19,9 +19,8 @@
 #include "util/sorted_uniform.hh"
 
 #include <algorithm>
-
 #include <stdint.h>
-#include <assert.h>
+#include <cassert>
 
 namespace lm {
 namespace ngram {
diff --git a/lm/blank.hh b/lm/blank.hh
index 94a71ad28..2107e1cb6 100644
--- a/lm/blank.hh
+++ b/lm/blank.hh
@@ -2,9 +2,8 @@
 #define LM_BLANK_H
 
 #include <limits>
-
 #include <stdint.h>
-#include <math.h>
+#include <cmath>
 
 namespace lm {
 namespace ngram {
diff --git a/lm/build_binary_main.cc b/lm/build_binary_main.cc
index 2af2222e3..6d88a398d 100644
--- a/lm/build_binary_main.cc
+++ b/lm/build_binary_main.cc
@@ -9,9 +9,8 @@
 #include <iostream>
 #include <iomanip>
 #include <limits>
-
-#include <math.h>
-#include <stdlib.h>
+#include <cmath>
+#include <cstdlib>
 
 #ifdef WIN32
 #include "util/getopt.hh"
diff --git a/lm/builder/interpolate.cc b/lm/builder/interpolate.cc
index 7de7852b9..0f9b98162 100644
--- a/lm/builder/interpolate.cc
+++ b/lm/builder/interpolate.cc
@@ -8,8 +8,8 @@
 #include "util/fixed_array.hh"
 #include "util/murmur_hash.hh"
 
-#include <assert.h>
-#include <math.h>
+#include <cassert>
+#include <cmath>
 
 namespace lm { namespace builder {
 namespace {
diff --git a/lm/builder/joint_order.hh b/lm/builder/joint_order.hh
index 9ed89097a..1728706dd 100644
--- a/lm/builder/joint_order.hh
+++ b/lm/builder/joint_order.hh
@@ -9,7 +9,7 @@
 #include <iostream>
 #endif
 
-#include <string.h>
+#include <cstring>
 
 namespace lm { namespace builder {
 
diff --git a/lm/builder/ngram.hh b/lm/builder/ngram.hh
index 0472bcb15..4525b3421 100644
--- a/lm/builder/ngram.hh
+++ b/lm/builder/ngram.hh
@@ -5,10 +5,9 @@
 #include "lm/word_index.hh"
 
 #include <cstddef>
-
-#include <assert.h>
+#include <cassert>
 #include <stdint.h>
-#include <string.h>
+#include <cstring>
 
 namespace lm {
 namespace builder {
diff --git a/lm/builder/print.cc b/lm/builder/print.cc
index bb9483333..2c8c7276c 100644
--- a/lm/builder/print.cc
+++ b/lm/builder/print.cc
@@ -7,8 +7,7 @@
 #include "util/stream/timer.hh"
 
 #include <sstream>
-
-#include <string.h>
+#include <cstring>
 
 namespace lm { namespace builder {
 
diff --git a/lm/builder/print.hh b/lm/builder/print.hh
index ba57f060a..ad282ea85 100644
--- a/lm/builder/print.hh
+++ b/lm/builder/print.hh
@@ -10,8 +10,7 @@
 #include "util/string_piece.hh"
 
 #include <ostream>
-
-#include <assert.h>
+#include <cassert>
 
 // Warning: print routines read all unigrams before all bigrams before all
 // trigrams etc.  So if other parts of the chain move jointly, you'll have to
diff --git a/lm/filter/arpa_io.cc b/lm/filter/arpa_io.cc
index f8568ac46..92c821aaf 100644
--- a/lm/filter/arpa_io.cc
+++ b/lm/filter/arpa_io.cc
@@ -6,9 +6,9 @@
 #include <string>
 #include <vector>
 
-#include <ctype.h>
-#include <errno.h>
-#include <string.h>
+#include <cctype>
+#include <cerrno>
+#include <cstring>
 
 namespace lm {
 
diff --git a/lm/filter/arpa_io.hh b/lm/filter/arpa_io.hh
index 99c97b11d..0f6c8be75 100644
--- a/lm/filter/arpa_io.hh
+++ b/lm/filter/arpa_io.hh
@@ -14,7 +14,7 @@
 #include <string>
 #include <vector>
 
-#include <string.h>
+#include <cstring>
 #include <stdint.h>
 
 namespace util { class FilePiece; }
diff --git a/lm/filter/phrase.cc b/lm/filter/phrase.cc
index e2946b145..345900ffa 100644
--- a/lm/filter/phrase.cc
+++ b/lm/filter/phrase.cc
@@ -9,7 +9,7 @@
 #include <string>
 #include <vector>
 
-#include <ctype.h>
+#include <cctype>
 
 namespace lm {
 namespace phrase {
diff --git a/lm/filter/vocab.cc b/lm/filter/vocab.cc
index 011ab5992..0a5585580 100644
--- a/lm/filter/vocab.cc
+++ b/lm/filter/vocab.cc
@@ -3,7 +3,7 @@
 #include <istream>
 #include <iostream>
 
-#include <ctype.h>
+#include <cctype>
 
 namespace lm {
 namespace vocab {
diff --git a/lm/lm_exception.cc b/lm/lm_exception.cc
index 0b572e984..58d468f30 100644
--- a/lm/lm_exception.cc
+++ b/lm/lm_exception.cc
@@ -1,7 +1,7 @@
 #include "lm/lm_exception.hh"
 
-#include<errno.h>
-#include<stdio.h>
+#include <cerrno>
+#include <cstdio>
 
 namespace lm {
 
diff --git a/lm/model.hh b/lm/model.hh
index 6925a56d0..c67ae2eed 100644
--- a/lm/model.hh
+++ b/lm/model.hh
@@ -17,8 +17,7 @@
 
 #include <algorithm>
 #include <vector>
-
-#include <string.h>
+#include <cstring>
 
 namespace util { class FilePiece; }
 
diff --git a/lm/model_test.cc b/lm/model_test.cc
index 0f54724bb..2e4b14fb4 100644
--- a/lm/model_test.cc
+++ b/lm/model_test.cc
@@ -1,7 +1,7 @@
 #include "lm/model.hh"
 
-#include <stdlib.h>
-#include <string.h>
+#include <cstdlib>
+#include <cstring>
 
 #define BOOST_TEST_MODULE ModelTest
 #include <boost/test/unit_test.hpp>
diff --git a/lm/ngram_query.hh b/lm/ngram_query.hh
index 5f330c5cc..560853749 100644
--- a/lm/ngram_query.hh
+++ b/lm/ngram_query.hh
@@ -11,8 +11,7 @@
 #include <ostream>
 #include <istream>
 #include <string>
-
-#include <math.h>
+#include <cmath>
 
 namespace lm {
 namespace ngram {
diff --git a/lm/partial.hh b/lm/partial.hh
index d8adc6965..3e67d91c5 100644
--- a/lm/partial.hh
+++ b/lm/partial.hh
@@ -5,8 +5,7 @@
 #include "lm/state.hh"
 
 #include <algorithm>
-
-#include <assert.h>
+#include <cassert>
 
 namespace lm {
 namespace ngram {
diff --git a/lm/read_arpa.cc b/lm/read_arpa.cc
index fb8bbfa28..9d46bdb34 100644
--- a/lm/read_arpa.cc
+++ b/lm/read_arpa.cc
@@ -9,8 +9,8 @@
 #include <sstream>
 #include <vector>
 
-#include <ctype.h>
-#include <string.h>
+#include <cctype>
+#include <cstring>
 #include <stdint.h>
 
 #ifdef WIN32
diff --git a/lm/search_trie.hh b/lm/search_trie.hh
index d8838d2ba..1adba6e5e 100644
--- a/lm/search_trie.hh
+++ b/lm/search_trie.hh
@@ -12,8 +12,7 @@
 
 #include <vector>
 #include <cstdlib>
-
-#include <assert.h>
+#include <cassert>
 
 namespace lm {
 namespace ngram {
diff --git a/lm/state.hh b/lm/state.hh
index f6c51d6f1..d9ba596ad 100644
--- a/lm/state.hh
+++ b/lm/state.hh
@@ -5,7 +5,7 @@
 #include "lm/word_index.hh"
 #include "util/murmur_hash.hh"
 
-#include <string.h>
+#include <cstring>
 
 namespace lm {
 namespace ngram {
diff --git a/lm/trie.cc b/lm/trie.cc
index 5f8e7ce78..93320a332 100644
--- a/lm/trie.cc
+++ b/lm/trie.cc
@@ -5,7 +5,7 @@
 #include "util/exception.hh"
 #include "util/sorted_uniform.hh"
 
-#include <assert.h>
+#include <cassert>
 
 namespace lm {
 namespace ngram {
diff --git a/lm/virtual_interface.hh b/lm/virtual_interface.hh
index 2a2690e14..e138ac14e 100644
--- a/lm/virtual_interface.hh
+++ b/lm/virtual_interface.hh
@@ -6,7 +6,7 @@
 #include "util/string_piece.hh"
 
 #include <string>
-#include <string.h>
+#include <cstring>
 
 namespace lm {
 namespace base {
diff --git a/lm/vocab.cc b/lm/vocab.cc
index 2285d279b..4fad78964 100644
--- a/lm/vocab.cc
+++ b/lm/vocab.cc
@@ -12,8 +12,7 @@
 #include "util/probing_hash_table.hh"
 
 #include <string>
-
-#include <string.h>
+#include <cstring>
 
 namespace lm {
 namespace ngram {
diff --git a/lm/word_index.hh b/lm/word_index.hh
index a5a0fda81..ad59a7c2f 100644
--- a/lm/word_index.hh
+++ b/lm/word_index.hh
@@ -2,7 +2,7 @@
 #ifndef LM_WORD_INDEX_H
 #define LM_WORD_INDEX_H
 
-#include <limits.h>
+#include <climits>
 
 namespace lm {
 typedef unsigned int WordIndex;
diff --git a/lm/wrappers/nplm.cc b/lm/wrappers/nplm.cc
index 44fd75a83..edc7b5b72 100644
--- a/lm/wrappers/nplm.cc
+++ b/lm/wrappers/nplm.cc
@@ -3,8 +3,7 @@
 #include "util/file.hh"
 
 #include <algorithm>
-
-#include <string.h>
+#include <cstring>
 
 #include "neuralLM.h"
 
diff --git a/util/bit_packing.cc b/util/bit_packing.cc
index 41999b726..d3f998d46 100644
--- a/util/bit_packing.cc
+++ b/util/bit_packing.cc
@@ -1,7 +1,7 @@
 #include "util/bit_packing.hh"
 #include "util/exception.hh"
 
-#include <string.h>
+#include <cstring>
 
 namespace util {
 
diff --git a/util/bit_packing.hh b/util/bit_packing.hh
index 1e34d9ab1..3cf3cd4a1 100644
--- a/util/bit_packing.hh
+++ b/util/bit_packing.hh
@@ -18,7 +18,7 @@
  * NICT.
  */
 
-#include <assert.h>
+#include <cassert>
 #ifdef __APPLE__
 #include <architecture/byte_order.h>
 #elif __linux__
@@ -28,8 +28,7 @@
 #endif 
 
 #include <stdint.h>
-
-#include <string.h>
+#include <cstring>
 
 namespace util {
 
diff --git a/util/bit_packing_test.cc b/util/bit_packing_test.cc
index 4edc2004c..c4494b69f 100644
--- a/util/bit_packing_test.cc
+++ b/util/bit_packing_test.cc
@@ -3,7 +3,7 @@
 #define BOOST_TEST_MODULE BitPackingTest
 #include <boost/test/unit_test.hpp>
 
-#include <string.h>
+#include <cstring>
 
 namespace util {
 namespace {
diff --git a/util/cat_compressed_main.cc b/util/cat_compressed_main.cc
index 2b4d72927..9ec8e81f7 100644
--- a/util/cat_compressed_main.cc
+++ b/util/cat_compressed_main.cc
@@ -2,7 +2,7 @@
 #include "util/file.hh"
 #include "util/read_compressed.hh"
 
-#include <string.h>
+#include <cstring>
 #include <iostream>
 
 namespace {
diff --git a/util/double-conversion/bignum-dtoa.cc b/util/double-conversion/bignum-dtoa.cc
index b6c2e85d1..3d217bf02 100644
--- a/util/double-conversion/bignum-dtoa.cc
+++ b/util/double-conversion/bignum-dtoa.cc
@@ -25,7 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include <math.h>
+#include <cmath>
 
 #include "bignum-dtoa.h"
 
diff --git a/util/double-conversion/cached-powers.cc b/util/double-conversion/cached-powers.cc
index c67642919..9dcfa3673 100644
--- a/util/double-conversion/cached-powers.cc
+++ b/util/double-conversion/cached-powers.cc
@@ -25,9 +25,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include <stdarg.h>
-#include <limits.h>
-#include <math.h>
+#include <cstdarg>
+#include <climits>
+#include <cmath>
 
 #include "utils.h"
 
diff --git a/util/double-conversion/double-conversion.cc b/util/double-conversion/double-conversion.cc
index febba6cd7..8a7923c5c 100644
--- a/util/double-conversion/double-conversion.cc
+++ b/util/double-conversion/double-conversion.cc
@@ -25,8 +25,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include <limits.h>
-#include <math.h>
+#include <climits>
+#include <cmath>
 
 #include "double-conversion.h"
 
diff --git a/util/double-conversion/fixed-dtoa.cc b/util/double-conversion/fixed-dtoa.cc
index d56b1449b..7c1a95278 100644
--- a/util/double-conversion/fixed-dtoa.cc
+++ b/util/double-conversion/fixed-dtoa.cc
@@ -25,7 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include <math.h>
+#include <cmath>
 
 #include "fixed-dtoa.h"
 #include "ieee.h"
diff --git a/util/double-conversion/strtod.cc b/util/double-conversion/strtod.cc
index e298766a2..55b4daa5d 100644
--- a/util/double-conversion/strtod.cc
+++ b/util/double-conversion/strtod.cc
@@ -25,8 +25,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include <stdarg.h>
-#include <limits.h>
+#include <cstdarg>
+#include <climits>
 
 #include "strtod.h"
 #include "bignum.h"
diff --git a/util/ersatz_progress.hh b/util/ersatz_progress.hh
index 535dbde23..b3bef7fa6 100644
--- a/util/ersatz_progress.hh
+++ b/util/ersatz_progress.hh
@@ -3,7 +3,6 @@
 
 #include <iostream>
 #include <string>
-
 #include <stdint.h>
 
 // Ersatz version of boost::progress so core language model doesn't depend on
diff --git a/util/exception.cc b/util/exception.cc
index eaf4cbc21..32d48516a 100644
--- a/util/exception.cc
+++ b/util/exception.cc
@@ -4,8 +4,8 @@
 #include <typeinfo>
 #endif
 
-#include <errno.h>
-#include <string.h>
+#include <cerrno>
+#include <cstring>
 
 namespace util {
 
diff --git a/util/exception.hh b/util/exception.hh
index 4e50a6f3a..2b503e50e 100644
--- a/util/exception.hh
+++ b/util/exception.hh
@@ -5,7 +5,6 @@
 #include <limits>
 #include <sstream>
 #include <string>
-
 #include <stdint.h>
 
 namespace util {
diff --git a/util/file.cc b/util/file.cc
index aa61cf9a9..414d0471c 100644
--- a/util/file.cc
+++ b/util/file.cc
@@ -13,9 +13,9 @@
 #include <sstream>
 
 
-#include <assert.h>
-#include <errno.h>
-#include <limits.h>
+#include <cassert>
+#include <cerrno>
+#include <climits>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
diff --git a/util/file.hh b/util/file.hh
index 7204b6a04..ca52dbfba 100644
--- a/util/file.hh
+++ b/util/file.hh
@@ -8,7 +8,6 @@
 #include <cstddef>
 #include <cstdio>
 #include <string>
-
 #include <stdint.h>
 
 namespace util {
diff --git a/util/file_piece.cc b/util/file_piece.cc
index 4aaa250e3..37e492672 100644
--- a/util/file_piece.cc
+++ b/util/file_piece.cc
@@ -14,10 +14,9 @@
 #include <iostream>
 #include <string>
 #include <limits>
-
-#include <assert.h>
+#include <cassert>
 #include <fcntl.h>
-#include <stdlib.h>
+#include <cstdlib>
 #include <sys/types.h>
 #include <sys/stat.h>
 
diff --git a/util/file_piece.hh b/util/file_piece.hh
index 5495ddccc..35f5eb648 100644
--- a/util/file_piece.hh
+++ b/util/file_piece.hh
@@ -11,8 +11,7 @@
 #include <cstddef>
 #include <iosfwd>
 #include <string>
-
-#include <assert.h>
+#include <cassert>
 #include <stdint.h>
 
 namespace util {
diff --git a/util/file_piece_test.cc b/util/file_piece_test.cc
index 4361877fe..4a2a521ba 100644
--- a/util/file_piece_test.cc
+++ b/util/file_piece_test.cc
@@ -8,8 +8,7 @@
 #include <boost/test/unit_test.hpp>
 #include <fstream>
 #include <iostream>
-
-#include <stdio.h>
+#include <cstdio>
 #include <sys/types.h>
 #include <sys/stat.h>
 
diff --git a/util/fixed_array.hh b/util/fixed_array.hh
index 416b92f4e..e2aa8ae7d 100644
--- a/util/fixed_array.hh
+++ b/util/fixed_array.hh
@@ -5,8 +5,8 @@
 
 #include <cstddef>
 
-#include <assert.h>
-#include <stdlib.h>
+#include <cassert>
+#include <cstdlib>
 
 namespace util {
 
diff --git a/util/mmap.cc b/util/mmap.cc
index a3c8a0225..b91f181f4 100644
--- a/util/mmap.cc
+++ b/util/mmap.cc
@@ -11,11 +11,11 @@
 
 #include <iostream>
 
-#include <assert.h>
+#include <cassert>
 #include <fcntl.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <stdlib.h>
+#include <cstdlib>
 
 #if defined(_WIN32) || defined(_WIN64)
 #include <windows.h>
diff --git a/util/murmur_hash.cc b/util/murmur_hash.cc
index 189668c01..d04e6ecd0 100644
--- a/util/murmur_hash.cc
+++ b/util/murmur_hash.cc
@@ -11,7 +11,7 @@
  */
 
 #include "util/murmur_hash.hh"
-#include <string.h>
+#include <cstring>
 
 namespace util {
 
diff --git a/util/pcqueue.hh b/util/pcqueue.hh
index d2ffee777..f74ef18e8 100644
--- a/util/pcqueue.hh
+++ b/util/pcqueue.hh
@@ -8,7 +8,7 @@
 #include <boost/thread/mutex.hpp>
 #include <boost/utility.hpp>
 
-#include <errno.h>
+#include <cerrno>
 
 #ifdef __APPLE__
 #include <mach/semaphore.h>
diff --git a/util/pool.cc b/util/pool.cc
index 429ba1585..e0e4c61f6 100644
--- a/util/pool.cc
+++ b/util/pool.cc
@@ -2,7 +2,7 @@
 
 #include "util/scoped.hh"
 
-#include <stdlib.h>
+#include <cstdlib>
 
 namespace util {
 
diff --git a/util/pool.hh b/util/pool.hh
index 89e793d7e..fd55572cd 100644
--- a/util/pool.hh
+++ b/util/pool.hh
@@ -5,7 +5,6 @@
 #define UTIL_POOL_H
 
 #include <vector>
-
 #include <stdint.h>
 
 namespace util {
diff --git a/util/probing_hash_table.hh b/util/probing_hash_table.hh
index ea228dd9a..83fd0ec12 100644
--- a/util/probing_hash_table.hh
+++ b/util/probing_hash_table.hh
@@ -9,7 +9,7 @@
 #include <functional>
 #include <vector>
 
-#include <assert.h>
+#include <cassert>
 #include <stdint.h>
 
 namespace util {
diff --git a/util/probing_hash_table_test.cc b/util/probing_hash_table_test.cc
index 9f7948ce6..6ed541431 100644
--- a/util/probing_hash_table_test.cc
+++ b/util/probing_hash_table_test.cc
@@ -7,9 +7,9 @@
 #include <boost/test/unit_test.hpp>
 #include <boost/scoped_array.hpp>
 #include <boost/functional/hash.hpp>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <stdint.h>
 
 namespace util {
diff --git a/util/read_compressed.cc b/util/read_compressed.cc
index cee98040b..7f240dd7e 100644
--- a/util/read_compressed.cc
+++ b/util/read_compressed.cc
@@ -7,10 +7,10 @@
 #include <algorithm>
 #include <iostream>
 
-#include <assert.h>
-#include <limits.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cassert>
+#include <climits>
+#include <cstdlib>
+#include <cstring>
 
 #ifdef HAVE_ZLIB
 #include <zlib.h>
diff --git a/util/read_compressed.hh b/util/read_compressed.hh
index 767ee94b2..9b36f641c 100644
--- a/util/read_compressed.hh
+++ b/util/read_compressed.hh
@@ -5,7 +5,6 @@
 #include "util/scoped.hh"
 
 #include <cstddef>
-
 #include <stdint.h>
 
 namespace util {
diff --git a/util/read_compressed_test.cc b/util/read_compressed_test.cc
index 301e8f4b4..a983ca720 100644
--- a/util/read_compressed_test.cc
+++ b/util/read_compressed_test.cc
@@ -9,11 +9,10 @@
 
 #include <fstream>
 #include <string>
-
-#include <stdlib.h>
+#include <cstdlib>
 
 #if defined __MINGW32__
-#include <time.h>
+#include <ctime>
 #include <fcntl.h>
 
 #if !defined mkstemp
diff --git a/util/sized_iterator.hh b/util/sized_iterator.hh
index 75f6886f7..c28d8e02e 100644
--- a/util/sized_iterator.hh
+++ b/util/sized_iterator.hh
@@ -8,7 +8,7 @@
 #include <string>
 
 #include <stdint.h>
-#include <string.h>
+#include <cstring>
 
 namespace util {
 
diff --git a/util/sorted_uniform.hh b/util/sorted_uniform.hh
index a3f6d021d..3673a8b5d 100644
--- a/util/sorted_uniform.hh
+++ b/util/sorted_uniform.hh
@@ -3,8 +3,7 @@
 
 #include <algorithm>
 #include <cstddef>
-
-#include <assert.h>
+#include <cassert>
 #include <stdint.h>
 
 namespace util {
diff --git a/util/stream/chain.cc b/util/stream/chain.cc
index ce29e428c..7b68400a8 100644
--- a/util/stream/chain.cc
+++ b/util/stream/chain.cc
@@ -8,9 +8,7 @@
 #include <cstdlib>
 #include <new>
 #include <iostream>
-
 #include <stdint.h>
-#include <stdlib.h>
 
 namespace util {
 namespace stream {
diff --git a/util/stream/chain.hh b/util/stream/chain.hh
index 508650860..28dc8060e 100644
--- a/util/stream/chain.hh
+++ b/util/stream/chain.hh
@@ -10,8 +10,7 @@
 #include <boost/thread/thread.hpp>
 
 #include <cstddef>
-
-#include <assert.h>
+#include <cassert>
 
 namespace util {
 template <class T> class PCQueue;
diff --git a/util/stream/multi_progress.cc b/util/stream/multi_progress.cc
index 8ba10386b..7d6a6a73a 100644
--- a/util/stream/multi_progress.cc
+++ b/util/stream/multi_progress.cc
@@ -6,7 +6,7 @@
 #include <iostream>
 #include <limits>
 
-#include <string.h>
+#include <cstring>
 
 #if !defined(_WIN32) && !defined(_WIN64)
 #include <unistd.h>
diff --git a/util/stream/multi_progress.hh b/util/stream/multi_progress.hh
index 82e698a59..41d40075a 100644
--- a/util/stream/multi_progress.hh
+++ b/util/stream/multi_progress.hh
@@ -5,7 +5,6 @@
 #include <boost/thread/mutex.hpp>
 
 #include <cstddef>
-
 #include <stdint.h>
 
 namespace util { namespace stream {
diff --git a/util/stream/multi_stream.hh b/util/stream/multi_stream.hh
index 0ee7fab6f..2772a7081 100644
--- a/util/stream/multi_stream.hh
+++ b/util/stream/multi_stream.hh
@@ -9,8 +9,8 @@
 #include <cstddef>
 #include <new>
 
-#include <assert.h>
-#include <stdlib.h>
+#include <cassert>
+#include <cstdlib>
 
 namespace util { namespace stream {
 
diff --git a/util/stream/stream.hh b/util/stream/stream.hh
index 7ea1c9f70..0e37f5d51 100644
--- a/util/stream/stream.hh
+++ b/util/stream/stream.hh
@@ -5,7 +5,7 @@
 
 #include <boost/noncopyable.hpp>
 
-#include <assert.h>
+#include <cassert>
 #include <stdint.h>
 
 namespace util {
diff --git a/util/string_piece.cc b/util/string_piece.cc
index ec394b96b..180b4e434 100644
--- a/util/string_piece.cc
+++ b/util/string_piece.cc
@@ -5,8 +5,7 @@
 #include "util/string_piece.hh"
 
 #include <algorithm>
-
-#include <limits.h>
+#include <climits>
 
 #ifndef HAVE_ICU
 
diff --git a/util/string_piece.hh b/util/string_piece.hh
index 114e25473..9c4798217 100644
--- a/util/string_piece.hh
+++ b/util/string_piece.hh
@@ -85,7 +85,7 @@ inline bool starts_with(const StringPiece& longer, const StringPiece& prefix) {
 #include <algorithm>
 #include <cstddef>
 #include <string>
-#include <string.h>
+#include <cstring>
 
 #ifdef WIN32
 #undef max
diff --git a/util/thread_pool.hh b/util/thread_pool.hh
index d1a883a00..d385b1a74 100644
--- a/util/thread_pool.hh
+++ b/util/thread_pool.hh
@@ -8,8 +8,7 @@
 #include <boost/thread.hpp>
 
 #include <iostream>
-
-#include <stdlib.h>
+#include <cstdlib>
 
 namespace util {
 
diff --git a/util/tokenize_piece.hh b/util/tokenize_piece.hh
index 908c8dafe..8621705e8 100644
--- a/util/tokenize_piece.hh
+++ b/util/tokenize_piece.hh
@@ -7,8 +7,7 @@
 #include <boost/iterator/iterator_facade.hpp>
 
 #include <algorithm>
-
-#include <string.h>
+#include <cstring>
 
 namespace util {
 
diff --git a/util/usage.cc b/util/usage.cc
index a597300e3..bbb209306 100644
--- a/util/usage.cc
+++ b/util/usage.cc
@@ -7,10 +7,9 @@
 #include <sstream>
 #include <set>
 #include <string>
-
-#include <string.h>
-#include <ctype.h>
-#include <time.h>
+#include <cstring>
+#include <cctype>
+#include <ctime>
 #if defined(_WIN32) || defined(_WIN64)
 // This code lifted from physmem.c in gnulib.  See the copyright statement
 // below.  
diff --git a/util/usage.hh b/util/usage.hh
index e578b0a65..85bd2119a 100644
--- a/util/usage.hh
+++ b/util/usage.hh
@@ -3,7 +3,6 @@
 #include <cstddef>
 #include <iosfwd>
 #include <string>
-
 #include <stdint.h>
 
 namespace util {