diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index dc47c47..85b582c 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -3409,6 +3409,10 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
 				(errcode_for_file_access(),
 				 errmsg("could not create file \"%s\": %m", tmppath)));
 
+#if defined(HAVE_FALLOCATE)
+	fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, XLogSegSize);
+#endif
+
 	/*
 	 * Zero-fill the file.	We have to do this the hard way to ensure that all
 	 * the file space has really been allocated --- on platforms that allow