--- a/env.c	Sun Mar 20 11:25:28 2016 +0100
+++ b/env.c	Sun Mar 20 11:25:41 2016 +0100
@@ -40,7 +40,7 @@
             if (p[1] != 1 && p[1] != 2)
                 close(p[1]);
             close(p[0]);
-            execlp("/bin/sh", "/bin/sh", "-c", command, 0);
+            execlp("/bin/sh", "/bin/sh", "-c", command, (char*)NULL);
             error("/bin/sh exec error");
         case -1:
             error("Fork error");