diff --git a/configure.ac b/configure.ac
index e72e3b9..ba3d271 100644
--- a/configure.ac
+++ b/configure.ac
@@ -722,7 +722,7 @@ if ! test "x$have_clock_gettime" = xno; then
     LIBS="$CLOCK_LIBS"
 
     AC_RUN_IFELSE([
-#define _POSIX_C_SOURCE 199309L
+#define _POSIX_C_SOURCE 200112L
 #include <time.h>
 
 int main(int argc, char *argv[[]]) {