diff --git a/lib/linebuffer.c b/lib/linebuffer.c
index 770ad62aa..e169a989d 100644
--- a/lib/linebuffer.c
+++ b/lib/linebuffer.c
@@ -24,13 +24,12 @@
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/types.h>
 #include "linebuffer.h"
 #include "unlocked-io.h"
 #include "xalloc.h"
 
-void free ();
-
 /* Initialize linebuffer LINEBUFFER for use. */
 
 void