diff --git a/configure.ac b/configure.ac
index f7d6fe5f..53165d79 100644
--- a/configure.ac
+++ b/configure.ac
@@ -38,7 +38,11 @@ AC_TYPE_UINT32_T
 AC_TYPE_UINT64_T
 AC_TYPE_UINT8_T
 AC_TYPE_INT8_T
-AC_CHECK_MEMBERS([struct stat.st_mtim.tv_nsec, struct stat.st_mtimensec, struct stat.st_mtimespec.tv_nsec], [], [], [[#include <sys/stat.h>]])
+AC_CHECK_MEMBERS([struct stat.st_mtim.tv_nsec, struct stat.st_mtimensec, struct stat.st_mtimespec.tv_nsec], [], [], [[
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+]])
 
 dnl Checks for library functions.
 AC_SYS_LARGEFILE
diff --git a/portable.h b/portable.h
index 9f67d682..e4e5805f 100644
--- a/portable.h
+++ b/portable.h
@@ -125,9 +125,9 @@
 #if HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC
 #define STAT_NSEC(st) (st)->st_mtim.tv_nsec /* Linux */
 #elif HAVE_STRUCT_STAT_ST_MTIMENSEC
-#define STAT_NSEC(st) (st)->st_mtimensec /* FreeBSD, Mac OS X if _POSIX_C_SOURCE defined */
+#define STAT_NSEC(st) (st)->st_mtimensec /* NetBSD */
 #elif HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC
-#define STAT_NSEC(st) (st)->st_mtimespec.tv_nsec /* Mac OS X if _POSIX_C_SOURCE not defined */
+#define STAT_NSEC(st) (st)->st_mtimespec.tv_nsec /* FreeBSD, Mac OS X */
 #else
 /**
  * If nanoseconds are not supported, we report the special FILE_MTIME_NSEC_INVALID value,