diff -uNr qemu-2.12.1/net/tap.c qemu-2.12.1.mod/net/tap.c
--- qemu-2.12.1/net/tap.c	2018-08-03 00:48:53.000000000 +0300
+++ qemu-2.12.1.mod/net/tap.c	2018-09-17 16:27:47.014062580 +0300
@@ -526,7 +526,7 @@
             *parg++ = helper_cmd;
             *parg++ = NULL;
 
-            execv("/bin/sh", args);
+            execv("@TERMUX_PREFIX@/bin/sh", args);
         } else {
             /* assume helper is just the executable path name */