diff --git a/src/main.c b/src/main.c
index 969e287..298112d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,6 +7,7 @@
  * (at your option) any later version.
  */
 
+#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <ev.h>
@@ -273,7 +274,7 @@ static int tip_client_head_hdr(struct tip_client *cli)
 		return -1;
 	}
 
-	if (posix_fallocate(cli->fd, 0, cli->content_len) < 0) {
+	if (fallocate(cli->fd, 0, 0, cli->content_len) < 0) {
 		syslog(LOG_ERR, "failed to allocate room for file %s: %s",
 		       filename, strerror(errno));
 		return -1;