diff --git a/src/CLI2.cpp b/src/CLI2.cpp
index aad608ef9..3f8e3853c 100644
--- a/src/CLI2.cpp
+++ b/src/CLI2.cpp
@@ -28,7 +28,7 @@
 #include <CLI2.h>
 #include <sstream>
 #include <algorithm>
-#include <stdlib.h>
+#include <cstdlib>
 #include <Context.h>
 #include <Lexer.h>
 #include <Color.h>
diff --git a/src/Context.cpp b/src/Context.cpp
index 988bc74e5..cc48c5ffd 100644
--- a/src/Context.cpp
+++ b/src/Context.cpp
@@ -31,9 +31,9 @@
 #include <sstream>
 #include <iomanip>
 #include <algorithm>
-#include <assert.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cassert>
+#include <cstdlib>
+#include <cstring>
 #include <unistd.h>
 #include <FS.h>
 #include <Eval.h>
@@ -48,7 +48,7 @@
 #include <commit.h>
 #endif
 
-#include <stdio.h>
+#include <cstdio>
 #include <sys/ioctl.h>
 
 #ifdef SOLARIS
diff --git a/src/DOM.cpp b/src/DOM.cpp
index 33573be8c..ed1be1b4a 100644
--- a/src/DOM.cpp
+++ b/src/DOM.cpp
@@ -28,7 +28,7 @@
 #include <DOM.h>
 #include <sstream>
 #include <map>
-#include <stdlib.h>
+#include <cstdlib>
 #include <Variant.h>
 #include <Lexer.h>
 #include <Context.h>
diff --git a/src/Eval.cpp b/src/Eval.cpp
index 69aeeac21..d2b9bfeff 100644
--- a/src/Eval.cpp
+++ b/src/Eval.cpp
@@ -27,7 +27,7 @@
 #include <cmake.h>
 #include <Eval.h>
 #include <map>
-#include <time.h>
+#include <ctime>
 #include <Context.h>
 #include <Task.h>
 #include <Color.h>
diff --git a/src/Hooks.cpp b/src/Hooks.cpp
index 05eba2e14..496104107 100644
--- a/src/Hooks.cpp
+++ b/src/Hooks.cpp
@@ -32,7 +32,7 @@
 #ifdef FREEBSD
 #define _WITH_GETLINE
 #endif
-#include <stdio.h>
+#include <cstdio>
 #include <unistd.h>
 #include <sys/wait.h>
 #include <sys/types.h>
diff --git a/src/Lexer.cpp b/src/Lexer.cpp
index 39e8866d6..4b9349208 100644
--- a/src/Lexer.cpp
+++ b/src/Lexer.cpp
@@ -27,7 +27,7 @@
 #include <cmake.h>
 #include <Lexer.h>
 #include <algorithm>
-#include <ctype.h>
+#include <cctype>
 #include <Datetime.h>
 #include <Duration.h>
 #include <unicode.h>
diff --git a/src/TDB2.cpp b/src/TDB2.cpp
index 6d224189f..004b30454 100644
--- a/src/TDB2.cpp
+++ b/src/TDB2.cpp
@@ -31,8 +31,8 @@
 #include <algorithm>
 #include <list>
 #include <set>
-#include <stdlib.h>
-#include <signal.h>
+#include <cstdlib>
+#include <csignal>
 #include <Context.h>
 #include <Color.h>
 #include <Datetime.h>
diff --git a/src/TLSClient.cpp b/src/TLSClient.cpp
index 4916e1e81..993925691 100644
--- a/src/TLSClient.cpp
+++ b/src/TLSClient.cpp
@@ -31,17 +31,13 @@
 #include <TLSClient.h>
 #include <iostream>
 #include <unistd.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdint.h>
-#include <string.h>
+#include <cstdio>
+#include <cstdlib>
+#include <cstdint>
+#include <cstring>
 #include <sys/socket.h>
 #include <arpa/inet.h>
-#if (defined OPENBSD || defined SOLARIS || defined NETBSD)
-#include <errno.h>
-#else
-#include <sys/errno.h>
-#endif
+#include <cerrno>
 #include <sys/types.h>
 #include <netdb.h>
 #include <gnutls/x509.h>
diff --git a/src/Task.cpp b/src/Task.cpp
index c93810582..922eac4ec 100644
--- a/src/Task.cpp
+++ b/src/Task.cpp
@@ -27,12 +27,12 @@
 #include <cmake.h>
 #include <Task.h>
 #include <sstream>
-#include <stdlib.h>
-#include <assert.h>
+#include <cstdlib>
+#include <cassert>
 #include <string>
 #ifdef PRODUCT_TASKWARRIOR
-#include <math.h>
-#include <ctype.h>
+#include <cmath>
+#include <cctype>
 #endif
 #include <cfloat>
 #include <algorithm>
diff --git a/src/Variant.cpp b/src/Variant.cpp
index b755d7d04..3862aa58f 100644
--- a/src/Variant.cpp
+++ b/src/Variant.cpp
@@ -28,9 +28,9 @@
 #include <sstream>
 #include <algorithm>
 #include <utility>
-#include <stdio.h>
-#include <math.h>
-#include <stdlib.h>
+#include <cstdio>
+#include <cmath>
+#include <cstdlib>
 #include <Variant.h>
 #include <Datetime.h>
 #include <Duration.h>
diff --git a/src/calc.cpp b/src/calc.cpp
index 27bc4dda6..e4ef01229 100644
--- a/src/calc.cpp
+++ b/src/calc.cpp
@@ -27,8 +27,8 @@
 #include <cmake.h>
 #include <iostream>
 #include <string>
-#include <stdlib.h>
-#include <string.h>
+#include <cstdlib>
+#include <cstring>
 #include <Eval.h>
 #include <Context.h>
 #include <Task.h>
diff --git a/src/feedback.cpp b/src/feedback.cpp
index 40a0c9e73..19e6c078f 100644
--- a/src/feedback.cpp
+++ b/src/feedback.cpp
@@ -30,8 +30,8 @@
 #include <sstream>
 #include <vector>
 #include <string>
-#include <stdlib.h>
-#include <inttypes.h>
+#include <cstdlib>
+#include <cinttypes>
 #include <Context.h>
 #include <Datetime.h>
 #include <Duration.h>
diff --git a/src/recur.cpp b/src/recur.cpp
index 479b1e470..70703e4dc 100644
--- a/src/recur.cpp
+++ b/src/recur.cpp
@@ -30,13 +30,13 @@
 #include <fstream>
 #include <sstream>
 #include <sys/types.h>
-#include <inttypes.h>
-#include <stdio.h>
-#include <string.h>
+#include <cinttypes>
+#include <cstdio>
+#include <cstring>
 #include <unistd.h>
-#include <stdlib.h>
+#include <cstdlib>
 #include <pwd.h>
-#include <time.h>
+#include <ctime>
 #include <Context.h>
 #include <Lexer.h>
 #include <Datetime.h>
diff --git a/src/rules.cpp b/src/rules.cpp
index 1d67624cb..494150305 100644
--- a/src/rules.cpp
+++ b/src/rules.cpp
@@ -25,7 +25,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 #include <cmake.h>
-#include <stdlib.h>
+#include <cstdlib>
 #include <Context.h>
 #include <Datetime.h>
 #include <shared.h>
diff --git a/src/sort.cpp b/src/sort.cpp
index 7a7e7eafb..3f13f9201 100644
--- a/src/sort.cpp
+++ b/src/sort.cpp
@@ -30,7 +30,7 @@
 #include <list>
 #include <map>
 #include <string>
-#include <stdlib.h>
+#include <cstdlib>
 #include <Context.h>
 #include <Duration.h>
 #include <Task.h>
diff --git a/src/util.cpp b/src/util.cpp
index e1e0b8158..814f9aa61 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -31,7 +31,7 @@
 #ifdef FREEBSD
 #define _WITH_GETLINE
 #endif
-#include <stdio.h>
+#include <cstdio>
 #include <iostream>
 #include <fstream>
 #include <sstream>
@@ -39,16 +39,16 @@
 #include <algorithm>
 #include <cstring>
 #include <string>
-#include <stdint.h>
+#include <cstdint>
 #include <sys/types.h>
 #include <sys/time.h>
 #include <sys/wait.h>
 #include <unistd.h>
-#include <stdlib.h>
-#include <string.h>
-#include <signal.h>
+#include <cstdlib>
+#include <cstring>
+#include <csignal>
 #include <pwd.h>
-#include <signal.h>
+#include <csignal>
 #include <sys/select.h>
 #include <Lexer.h>
 #include <unicode.h>