Remove malloc warning.
diff --git a/iptables-standalone.c b/iptables-standalone.c
index 53d2189..7bd3a48 100644
--- a/iptables-standalone.c
+++ b/iptables-standalone.c
@@ -25,6 +25,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <errno.h>
 #include <iptables.h>