diff --git a/src/common.c b/src/common.c
index abd847b..a2d23f8 100644
--- a/src/common.c
+++ b/src/common.c
@@ -130,6 +130,10 @@ open_dns(int localport, in_addr_t listen_ip)
 	setsockopt(fd, IPPROTO_IP, DSTADDR_SOCKOPT, (const void*) &flag, sizeof(flag));
 #endif
 
+	/* Set dont-fragment ip header flag */
+	flag = DONT_FRAG_VALUE;
+	setsockopt(fd, IPPROTO_IP, IP_OPT_DONT_FRAG, (const void*) &flag, sizeof(flag));
+
 	if(bind(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) 
 		err(1, "bind");
 
diff --git a/src/common.h b/src/common.h
index 5daef40..a6d1137 100644
--- a/src/common.h
+++ b/src/common.h
@@ -19,7 +19,6 @@
 
 #ifdef WINDOWS32
 #include "windows.h"
-#include <winsock.h>
 #else
 #include <sys/socket.h>
 #include <err.h>
@@ -45,6 +44,20 @@
 # define dstaddr(x) (&(((struct in_pktinfo *)(CMSG_DATA(x)))->ipi_addr)) 
 #endif
 
+#if defined IP_MTUDISC
+# define IP_OPT_DONT_FRAG IP_MTUDISC
+# define DONT_FRAG_VALUE 1
+#elif defined IP_MTU_DISCOVER
+# define IP_OPT_DONT_FRAG IP_MTU_DISCOVER
+# define DONT_FRAG_VALUE IP_PMTUDISC_DO
+#elif defined IP_DONTFRAG
+# define IP_OPT_DONT_FRAG IP_DONTFRAG
+# define DONT_FRAG_VALUE 1
+#elif defined IP_DONTFRAGMENT
+# define IP_OPT_DONT_FRAG IP_DONTFRAGMENT
+# define DONT_FRAG_VALUE 1
+#endif
+
 struct packet 
 {
 	int len;		/* Total packet length */