diff --git a/src/slirp.c b/src/slirp.c
index b0194cb..3fd6f68 100644
--- a/src/slirp.c
+++ b/src/slirp.c
@@ -890,20 +890,22 @@ static int if_encap6(Slirp *slirp, struct mbuf *ifm, struct ethhdr *eh,
  */
 int if_encap(Slirp *slirp, struct mbuf *ifm)
 {
-    uint8_t buf[1600];
-    struct ethhdr *eh = (struct ethhdr *)buf;
+    uint8_t *buf;
+    struct ethhdr *eh;
     uint8_t ethaddr[ETH_ALEN];
     const struct ip *iph = (const struct ip *)ifm->m_data;
     int ret;
 
-    if (ifm->m_len + ETH_HLEN > sizeof(buf)) {
-        return 1;
-    }
+    buf = g_malloc(ifm->m_len + ETH_HLEN);
+    if (!buf)
+        return 0;
+    eh = (struct ethhdr *)buf;
 
     switch (iph->ip_v) {
     case IPVERSION:
         ret = if_encap4(slirp, ifm, eh, ethaddr);
         if (ret < 2) {
+            g_free(buf);
             return ret;
         }
         break;
@@ -911,6 +913,7 @@ int if_encap(Slirp *slirp, struct mbuf *ifm)
     case IP6VERSION:
         ret = if_encap6(slirp, ifm, eh, ethaddr);
         if (ret < 2) {
+            g_free(buf);
             return ret;
         }
         break;
@@ -929,6 +932,7 @@ int if_encap(Slirp *slirp, struct mbuf *ifm)
               eh->h_dest[5]);
     memcpy(buf + sizeof(struct ethhdr), ifm->m_data, ifm->m_len);
     slirp_send_packet_all(slirp, buf, ifm->m_len + ETH_HLEN);
+    g_free(buf);
     return 1;
 }