diff --git a/CMakeModules/UseCompat.cmake b/CMakeModules/UseCompat.cmake
index c1befd7..4cc1873 100644
--- a/CMakeModules/UseCompat.cmake
+++ b/CMakeModules/UseCompat.cmake
@@ -27,6 +27,7 @@
     set(CMAKE_REQUIRED_DEFINITIONS -D_POSIX_C_SOURCE=200809L)
     list(APPEND CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
     list(APPEND CMAKE_REQUIRED_DEFINITIONS -D__BSD_VISIBLE=1)
+    list(APPEND CMAKE_REQUIRED_DEFINITIONS -D_DEFAULT_SOURCE)
     set(CMAKE_REQUIRED_LIBRARIES pthread)
 
     check_symbol_exists(vdprintf "stdio.h;stdarg.h" HAVE_VDPRINTF)
@@ -54,6 +55,7 @@
     check_symbol_exists(realpath "stdlib.h" HAVE_REALPATH)
     check_symbol_exists(localtime_r "time.h" HAVE_LOCALTIME_R)
     check_symbol_exists(gmtime_r "time.h" HAVE_GMTIME_R)
+    check_symbol_exists(timegm "time.h" HAVE_TIMEGM)
     check_symbol_exists(strptime "time.h" HAVE_STRPTIME)
     check_symbol_exists(mmap "sys/mman.h" HAVE_MMAP)
     check_symbol_exists(dirname "libgen.h" HAVE_DIRNAME)
diff --git a/compat/compat.h.in b/compat/compat.h.in
index c697d6c..6df7a7b 100644
--- a/compat/compat.h.in
+++ b/compat/compat.h.in
@@ -70,6 +70,7 @@
 #cmakedefine HAVE_REALPATH
 #cmakedefine HAVE_LOCALTIME_R
 #cmakedefine HAVE_GMTIME_R
+#cmakedefine HAVE_TIMEGM
 #cmakedefine HAVE_STRPTIME
 #cmakedefine HAVE_MMAP
 #cmakedefine HAVE_DIRNAME
@@ -188,6 +189,14 @@
 struct tm *localtime_r(const time_t *timep, struct tm *result);
 #endif
 
+#ifndef HAVE_TIMEGM
+# if defined (_WIN32)
+#  define timegm _mkgmtime
+# else
+#  error No timegm() implementation for this platform is available.
+# endif
+#endif
+
 #ifndef HAVE_STRPTIME
 char *strptime(const char *s, const char *format, struct tm *tm);
 #endif