diff --git a/app/actions.cpp b/app/actions.cpp
index 479fa997..57945e33 100644
--- a/app/actions.cpp
+++ b/app/actions.cpp
@@ -26,7 +26,7 @@
 // + standard includes
 #include <sys/stat.h>   // for stat()
 #include <sys/types.h>  // for stat()
-#ifdef EXV_HAVE_UNISTD_H
+#if __has_include(<unistd.h>)
 #include <unistd.h>  // for stat()
 #endif
 
diff --git a/cmake/config.h.cmake b/cmake/config.h.cmake
index 581defda..7c6a2258 100644
--- a/cmake/config.h.cmake
+++ b/cmake/config.h.cmake
@@ -9,9 +9,6 @@
 // Define if you require webready support.
 #cmakedefine EXV_ENABLE_WEBREADY
 
-// Define if you have the <libintl.h> header file.
-#cmakedefine EXV_HAVE_LIBINTL_H
-
 // Define if you want translation of program messages to the user's native language
 #cmakedefine EXV_ENABLE_NLS
 
@@ -44,15 +41,6 @@
 // Define if you have the munmap function.
 #cmakedefine EXV_HAVE_MUNMAP
 
-/* Define if you have the <libproc.h> header file. */
-#cmakedefine EXV_HAVE_LIBPROC_H
-
-/* Define if you have the <unistd.h> header file. */
-#cmakedefine EXV_HAVE_UNISTD_H
-
-// Define if you have the <sys/mman.h> header file.
-#cmakedefine EXV_HAVE_SYS_MMAN_H
-
 // Define if you have the zlib library.
 #cmakedefine EXV_HAVE_LIBZ
 
diff --git a/samples/getopt-test.cpp b/samples/getopt-test.cpp
index 39aa93cf..719755b4 100644
--- a/samples/getopt-test.cpp
+++ b/samples/getopt-test.cpp
@@ -26,7 +26,7 @@
 // getopt.{cpp|hpp} is not part of libexiv2
 #include "getopt.hpp"
 
-#ifdef EXV_HAVE_UNISTD_H
+#if __has_include(<unistd.h>)
 #include <unistd.h>
 #endif
 #include <iostream>
@@ -79,7 +79,7 @@ int main(int argc, char** const argv) {
 
   int n;
 
-#ifdef EXV_HAVE_UNISTD_H
+#if __has_include(<unistd.h>)
   std::cout << "standard getopt()" << std::endl;
   do {
     n = ::getopt(argc, argv, ::optstring);
diff --git a/src/basicio.cpp b/src/basicio.cpp
index fdbc5697..c23a47bc 100644
--- a/src/basicio.cpp
+++ b/src/basicio.cpp
@@ -11,10 +11,6 @@
 #include "image_int.hpp"
 #include "types.hpp"
 
-// + standard includes
-#include <fcntl.h>     // _O_BINARY in FileIo::FileIo
-#include <sys/stat.h>  // for stat, chmod
-
 #include <cstdio>   // for remove, rename
 #include <cstdlib>  // for alloc, realloc, free
 #include <cstring>  // std::memcpy
@@ -22,14 +18,18 @@
 #include <fstream>  // write the temporary file
 #include <iostream>
 
-#ifdef EXV_HAVE_SYS_MMAN_H
+// + standard includes
+#include <fcntl.h>     // _O_BINARY in FileIo::FileIo
+#include <sys/stat.h>  // for stat, chmod
+
+#if __has_include(<sys/mman.h>)
 #include <sys/mman.h>  // for mmap and munmap
 #endif
-#ifdef EXV_HAVE_PROCESS_H
+#if __has_include(<process.h>)
 #include <process.h>
 #endif
-#ifdef EXV_HAVE_UNISTD_H
-#include <unistd.h>  // for getpid, stat
+#if __has_include(<unistd.h>)
+#include <unistd.h>
 #endif
 
 #ifdef EXV_USE_CURL
diff --git a/src/futils.cpp b/src/futils.cpp
index ddbbf0ac..cccb0ded 100644
--- a/src/futils.cpp
+++ b/src/futils.cpp
@@ -30,10 +30,14 @@ namespace fs = std::experimental::filesystem;
 // clang-format on
 #endif
 
-#if defined(__APPLE__) && defined(EXV_HAVE_LIBPROC_H)
+#if __has_include(<libproc.h>)
 #include <libproc.h>
 #endif
 
+#if __has_include(<unistd.h>)
+#include <unistd.h>  // for stat()
+#endif
+
 #if defined(__FreeBSD__)
 #include <libprocstat.h>
 #include <sys/mount.h>
@@ -45,10 +49,6 @@ namespace fs = std::experimental::filesystem;
 #include <sys/un.h>
 #endif
 
-#ifdef EXV_HAVE_UNISTD_H
-#include <unistd.h>  // for stat()
-#endif
-
 #ifndef _MAX_PATH
 #define _MAX_PATH 1024
 #endif
@@ -346,14 +346,12 @@ std::string getProcessPath() {
     }
     CloseHandle(processHandle);
   }
-#elif defined(__APPLE__)
-#ifdef EXV_HAVE_LIBPROC_H
+#elif __has_include(<libproc.h>)
   const int pid = getpid();
   char pathbuf[PROC_PIDPATHINFO_MAXSIZE];
   if (proc_pidpath(pid, pathbuf, sizeof(pathbuf)) > 0) {
     ret = pathbuf;
   }
-#endif
 #elif defined(__FreeBSD__)
   unsigned int n;
   char buffer[PATH_MAX] = {};
diff --git a/src/version.cpp b/src/version.cpp
index 0ccb7c12..b9c8bcc2 100644
--- a/src/version.cpp
+++ b/src/version.cpp
@@ -312,7 +312,7 @@ void Exiv2::dumpLibraryInfo(std::ostream& os, const std::vector<std::regex>& key
   int enable_video = 0;
   int use_curl = 0;
 
-#ifdef EXV_HAVE_INTTYPES_H
+#if __has_include(<inttypes.h>)
   have_inttypes = 1;
 #endif
 
@@ -324,21 +324,23 @@ void Exiv2::dumpLibraryInfo(std::ostream& os, const std::vector<std::regex>& key
   have_iconv = 1;
 #endif
 
-#ifdef EXV_HAVE_LIBINTL_H
+#if __has_include(<libintl.h>)
   have_libintl = 1;
 #endif
 
-#ifdef EXV_HAVE_MEMORY_H
+#if __has_include(<memory.h>)
   have_memory = 1;
 #endif
 
-#ifdef EXV_HAVE_STDBOOL_H
+#if __has_include(<stdbool.h>)
   have_stdbool = 1;
 #endif
 
+#if __has_include(<stdint.h>)
   have_stdint = 1;
+#endif
 
-#ifdef EXV_HAVE_STDLIB_H
+#if __has_include(<stdlib.h>)
   have_stdlib = 1;
 #endif
 
@@ -346,7 +348,7 @@ void Exiv2::dumpLibraryInfo(std::ostream& os, const std::vector<std::regex>& key
   have_strerror_r = 1;
 #endif
 
-#ifdef EXV_HAVE_STRINGS_H
+#if __has_include(<strings.h>)
   have_strings = 1;
 #endif
 
@@ -358,19 +360,19 @@ void Exiv2::dumpLibraryInfo(std::ostream& os, const std::vector<std::regex>& key
   have_munmap = 1;
 #endif
 
-#ifdef EXV_HAVE_SYS_STAT_H
+#if __has_include(<sys/stat.h>)
   have_sys_stat = 1;
 #endif
 
-#ifdef EXV_HAVE_SYS_TYPES_H
+#if __has_include(<sys/types.h>)
   have_sys_types = 1;
 #endif
 
-#ifdef EXV_HAVE_UNISTD_H
+#if __has_include(<unistd.h>)
   have_unistd = 1;
 #endif
 
-#ifdef EXV_HAVE_SYS_MMAN_H
+#if __has_include(<sys/mman.h>)
   have_sys_mman = 1;
 #endif
 
@@ -390,22 +392,6 @@ void Exiv2::dumpLibraryInfo(std::ostream& os, const std::vector<std::regex>& key
   adobe_xmpsdk = EXV_ADOBE_XMPSDK;
 #endif
 
-#ifdef EXV_HAVE_BOOL
-  have_bool = 1;
-#endif
-
-#ifdef EXV_HAVE_STRINGS
-  have_strings = 1;
-#endif
-
-#ifdef EXV_SYS_TYPES
-  have_sys_types = 1;
-#endif
-
-#ifdef EXV_HAVE_UNISTD
-  have_unistd = 1;
-#endif
-
 #ifdef EXV_ENABLE_BMFF
   enable_bmff = 1;
 #endif